senior editors and baseline quality
The general rule is that two people know more than one, and in the same way: two wikipedias know more than one. Yet that doesn't mean what they say is necessarily true. That's why we should have and follow guidelines about encyclopaedicity, neutrality, verifiability, balance and article coverage.
The tasks this task force envisioned for meta-projects are different from the things projects at wp-en are doing. Nevertheless, I am a member of the wikiproject:geology at wp-en and have its talk page on my watchlist. That particular project is working fine. When a user posts a certain question, I may answer. There are some 30 other geologists active on wp-en that may do the same.
Two people may know more than one if it comes down to a simple addition, but some of the things they know will contradict each other; the things they agree on knowing will be a lot less than what one person knows. As to the useful work they produce, there are many cases where two (or ten) people together do not produce half (or a tenth) the amount of work one person can do (if he knows what he is doing). It all depends. - Brya 05:43, 23 January 2010 (UTC)
Indeed, the idea is not to keep such a project as an elite club, but more as a driving force. A simple example: today as an admin I had to make a decision on an article about a computer game. I have myself no idea about the computer games. The deletion review was not active, only the author of the article voted (obviously, against deletion). What I did I went to the computer games project, asked their opinion, and eventually deleted the article. That was my responsibility, but eventually their expertise.