I've noticed a excellent trend towards achieving consistency lately. The WikiProject was an attempt to instill some consistency back in the days when achieving that was (software-wise) far more difficult. As you pointed out it did not adequately include naming conventions. I think a namespace for such things would be beneficial. I actually don't care what the namespace, as long as it is easy to use. A "Wikiproject" namespace has a few arguments for it - it's obviously NOT an article topic (unlike "conventions" or similar). Also a lot of work has already been done using this name so changing it would take some editing.
I don't see any need for more namespaces for this or for "almanac" entries. They're a great feature, but let's not just add them willy-nilly without some forethought about organization and growth. As I see it, the primary use of namespaces is to distinguish "regular" articles from meta-stuff "about" wikipedia which the software has to treat specially. In general, all meta stuff not already in another namespace can go into "wikipedia:". If you want to move the Wikiproject stuff under Wikipedia:Pojects or wherever, that's a good idea. I was kind of in the process of cleaning up the main namespace when I got sidetracked into doing the software, but I'd like to get back into that.
Don't move the naming conventions page--it's tied in with the other general policy pages and fits well. Of course, specific things like ship names, cities, etc., could still have their own pages and be linked to both from the projects page and from naming conventions.
A few other namespaces are quite reasonable; "User" has some special features in the software, so that stays. Likewise the corresponding Talk pages of the other namespaces (every page needs to have talk about that page, and there are software features there too). In the new codebase I got rid of "Log" and moved those functions under Wikipedia: as well. I just didn't see any need for it. Alas, I had to add a namespace ("Image") to do some special features like link lists and history.
In general, I don't think new namespaces should be created without a specific need for the software to treat them differently. Currently, for example, the search function only searches in the primary namespace. If we created a "almanac" space, for example, we'd have to fix the software to search that as well, and that just adds complexity for no benefit. I see no problem at all with articles that today would be printed in an almanac. Just title them clearly (like "List of...") and go for it. 0
wikipedia-l@lists.wikimedia.org