Before I begin, I have CC'ed this message to the Wikipedia mailing list, as there is some relevance there. For Wikipedia list members, the original discussion refers to a proposal to modify deletion policy to allow a limited form of Wikipedia article forking in order to create a more in-depth guide to a topic in Wikibooks (which is currently against policy, see [[WB:WIN]]). It has evolved somewhat into a debate on what Wikibookians think of Wikibooks vs. what others (eg. Wikipedians) think of Wikibooks.
I guess that I'm trying to modify the deletion policy somewhat to allow *some* forking of Wikipedia content, provided that the content on Wikibooks really is an expansion of the Wikipedia article and not just some POV fight or fork of Wikipedia content. The nature of Wikibooks certainly allows almost any article on Wikipedia to be turned into a book, provided there are interested parties willing to write the content. Forbidding any fork would, in effect, kill almost any Wikibook stub right now.
We do not allow any content that isn't considered to be instructional material. The spirit of WB:WIN is that if you want to expand a WP article, then do it on WP. Personally, I am opposed to any Wikipedia forking in general because of the fact that I consider encyclopedia articles are not by itself instructional material. Based on your post, [[The Biography of Nikola Tesla]] would have been deleted whether we have the changed policy or not, due to it originating from an edit war.
I have to say that, to some real extent, the "books" part of Wikibooks is really a misnomer: it's not clearly intuitive that we are writing textbooks of instructional material on this wiki.
From following discussion on Foundation-l, it seems as though a number of people at Wikipedia and Meta have a very different opinion of what Wikibooks is all about, and it seems as though Wikibooks has in effect been turned into a general repository of non-fiction book-length topics. In particular, discussions around http://meta.wikimedia.org/wiki/Proposals_for_new_projects seem to indicate a more general attitude toward Wikibooks.
The original concept for Wikibooks, according to its founder, [[User:Karl Wick]] I believe, is a wiki for building textbooks. However, Wikipedians for some odd reason decided to offload their unwanted goods to Wikibooks: for examples, the VFD precedent there regarding recipes has largely been the driving force behind [[Cookbook]], even though a cooking textbook should focus little on recipes and more on general cooking techniques. Many of the books here have since defied their original intent: for example, [[Computer and video games bookshelf]] (originally [[Game Guides and Strategy]]) - a textbook on beating a computer game sounds ludicrous to me.
Wikibooks also suffers from the fact that there are few active admins and few active users of action (and thus suffering from repeated vandal attacks). Prior to myself becoming an admin, there were over 200 pages on speedy deletion, some of them being marked for months (although half of these were due to technical constraints). There are possibly another 200 pages that could be easily moved out of en: and onto their respective Wikibooks if only Special:Import was complete (or someone did hard transwiking). Because of this, few Wikibookians are willing to put down concrete policies that are followed and enforced (consider that key pages such as [[WB:HNS]], [[WB:FP]] and even [[WB:WIN]] were in constant flux). Furthermore, Wikibookians tend to be within their own group of books, and rarely venture into collaborating in other books (this is perhaps due to a lack of a consistent Manual of Style). This makes it difficult to judge the purpose of Wikibooks. Only recently have users decided to put their foot down in respect to what Wikibooks is about, and what it is about is instructional material. It could very well be the case that longtime existing books such as [[Jokebook]] could be put up in VFD for not being instructional material.
One of the problems that Wikibooks is suffering from right now is that Wikiversity is not really a successful project in itself. Yes, there is content there, but even project like Virtual University (http://www.vu.org/) show more of a real academic environment. Another one is Diversity University (http:// www.du.org/). Even if Wikiversity were brought up to these somewhat modest standards, the auxuallary role of Wikibooks would be considerably more apparant. Instead, Wikibooks is percieved as an auxuallary role to Wikipedia and the other "sister projects" of the Wikimedia Foundation, which has in effect a broading of scope effect to Wikibooks.
Last I checked, Wikiversity is more popular on de: than on en: to the point of making a separate wiki for it (de.wikiversity.org). The English version suffers from repeated content (the school for CS has a page on data structures when we already have [[Data Structures]], for example), and has been a frequent target for vandals, making it seem like (to me) an anachronism.
Part of the blame perhaps lies with the structure of Wikibooks: Wikiversity, as it was originally designed, is supposed to be broader in scope with the rest of Wikibooks, yet the wiki is -books and not - versity, implying that the books is bigger than the university, or that the university is a book... Now it's no more than a book that has special sidebar privileges.
On Wikibooks itself I've been involved with a minor edit war where some people have tried to come into one of the Wikibooks I've created and try to turn it into a subject-based Wikipedia, and I've resisted the effort, particuarly on the talk pages. Somehow the idea that content on Wikibooks should be a book rather than a bunch of web pages loosely connected does not always get across.
Point them to [[WB:WIN]]. A good many users are Wikipedians that think of Wikibooks as more in-depth. Wikibooks tries to teach as well, and that's something that isn't put across clearly in many books. Considering that it takes longer to write a book than a single encyclopedia article, I wouldn't consider it a surprise.
I guess what I'm trying to say is that Wikibooks is drifting from its original and noble foundations, and I really don't see significant effort to try and go back to those roots. Nor do I see any desire by the newer Wikibookians to try and follow that ideal, at least to the letter as supplimental materials to Wikiversity or to support specific academic standards requirements. Let me put it more directly and specifc then: How many Wikibooks that can be used as a textbook for any major college or university, or follows state or national academic requirements to be used as the basis for curriculm development as a textbook? The FHSST books are based on this type of standard, but that does come from outside Wikibooks to at least get it started. Books like "How to Build a Pykrete Bong" are more typical to Wikibooks, unfortunately.
You do have a point here. In this sense, Wikibooks as a project has been a failure.
I truly believe the original purpose has been lost, in part due to [[WB:FP]] forcing Wikibookians to perhaps making a one-size-fits-all book. A good many books today are "one-page books" (eg. How to do xxx), and may need to be merged together.
Furthermore, many of the books, such as our COTM, literally take "instructional material" to its limit. Is a travel guide considered instructional material? Only a trip to VFD can we find out - there has been no precedent in many cases where we could establish what we consider instructional material. The only major VFD debate going on with ramifications on how instruction material is defined is whether collaborative fiction for the purposes of education is allowed ([[Ardvark the Aardvark]]).
To date, the only real hardened concrete policies that we have is [[WB:AT]], as it deals with Wikisource (which seems to have its policies better enforced).
I fail to see what the origin of motivation for creating a Wikibook has to do with if it gets deleted or not. It should IMHO (and apparently this opinion is not shared) stand on its own merits independently of other content on other Wikimedia projects. I have posted requests for deletion for content that seems to be a pure fork of Wikipedia content (and nothing added) to Wikibooks, and there are several Wikibook modules that really do need to be deleted on this basis.
Agreed. Be bold and put it on VFD. In some cases put it on speedy.
There really isn't an effort on Wikipedia to allow book-length material either, which is one reason why the Nikola Tesla information was put here on Wikibooks. While part of an edit war, it seems as though contributors at Wikipedia are being told to go away, and that some admins at Wikibooks are saying the same thing. This is not a good thing to do in either case, and weakens both communities as a result. If, as you seem to suggest, that Wikibooks should be for pure textbook content, perhaps Wikibooks itself needs to fork and a separation between academic books and other non-fiction materials needs to take place.
Book-length material is inappropriate in Wikipedia because it goes too in-depth. It may or not be appropriate material in Wikibooks depending on whether the material is instructional in nature. For noninstructional material that could be book length (ie. a macropedia), we are truly stuck. IMO, Wikipedia is an encyclopedia, and its comprehensiveness should be able to take any reasonable topic and bring it to an arbitrary and acceptable level of depth. Wikibooks is an instructional resource - the same level of depth can only be reached only through tutoring its readers, and thus the two necessitate different approaches. A good example on what Wikipedia and Wikibooks should be in comparison to each other is how an article on arithmetic is clearly different from a book on arithmetic: the Wikipedia article should not teach you how to do arithmetic beyond "doing it", while the Wikibooks module should concern itself with strategies (eg. use manipulatives such as beans or candy) for doing it and less to do with the history of arithmetic, which is adequately covered by Wikipedia.