Just to put my oar in the water:
1) Why Nupedia isn't as "successful" as Wikipedia:
I can only tell you what I think (since I'm in arrears on a Nupedia article). First, I think Nupedia is in some ways the ideal -- partially because my understanding is that expertise can be demonstrated in ways other than credentials. Second, because there's peer review that means something -- review by other people who might know something about the subject. Finally, there's a copyediting standard. Why isn't it more successful? For me, it's two things -- the process is a bit unwieldy (I'd actually have to draft a complete article to submit it, which takes time -- probably a lot less than I spend here, but wikipedia nickels and dimes your time to death) and second.actually, it's really just what I said -- the process is a bit unwieldy -- it's not set up for people who have a few minutes here and there to do a quick edit or addition. Oh -- and frankly, online resources of any kind aren't really accepted yet by moat of academia (at least not the people in charge of hiring and granting tenure).
2) Re: Attracting experts: The estimable Mr. Gilbert said, "if you build it." I agree, but add (a la Mr F. Bauder) they will also leave when they get tired of the aggro. I think expert retention is more the problem -- there has been attrition, though, since I've been here. Let me first say that yes, ego is involved. Credentials do usually represent a huge amount of work and emotional investment, as does teaching a subject. So too with interested amateurs who have their own areas of expertise -- meaning they've done a lot of work and really learned their subjects. It doesn't mean we can't be wrong (Lord knows, I have my moments!), but it generally means we are, well, experts. That means that we do get irritated when we get into edit wars with people who know less and often express it even less well.
3) Retaining good people in general. I think it's part of getting bigger and having no staff -- it's like working in a successful start-up -- the initial employees are really tight and get so used to working together that they cooperate and play to each other's strengths without thinking. As the start-up grows, it starts to get a hierarchy, New people don't have the luxury of knowing who among their fellows is the go-to person for what, and there is sometimes friction. The difference here for me is, I don't think newbies have any excuse for not learning a bit about the old hands -- and I think they also have some responsibility to help make themselves known. I try to encourage people to tell us something about themselves when I say hi, but it might be nice to have a template for user pages with a space for "expertise" and "interests."
3 continued ) It might also be good to have links to Wikipedia etiquette on the user page -- or as part of the login process. DW, the person with shades of French Helganess, is contributing huge amounts, but refuses to respond to queries on whether his/her pictures and sources are PD, or to acknowledge my requests to look at how we've been formatting historical stuff. This is after accusing me of pushing everybody else around (not that I don't make cases for how I think things should be, but I generally have good reasons, and when I haven't, I hope I've given in gracefully.
Still -- the two things that have driven me off on "breaks" in the past (and most likely the future) are the lack of respect for my hard-earned knowledge and a general lack of communal cooperation from a very few (but for some reason, interested in history) people who make me thing "My time is too valuable for this -- I spend way more time fighting to make other people's articles *passable* than writing new stuff."
Anyway, that's my take. It would be really nice to have a few people with some official *moderator* position, but I can see how that could be a problem unless there are volunteers. In the meantime, I just thank goodness for the Vickis and Aprils and Mavs and Stephen Gilberts (etc -- I'm not leaving people out on purpose.) there are lots of good reasons to hang around!
Jules