I try to answer questions tagged mercurial since I'm a developer on that project. Like most open source projects, we also have a mailinglist, an IRC channel, a wiki, a book, etc online where people can get support, find tutorials, etc.
So when I first started here, I often felt that it would have been better overall if the question had been asked on our mailinglist instead: there is a large number of Mercurial users there and the question is seen by the core Mercurial developers. A typical example is this question about a feature — the developer who last worked on this would have read the question on the mailinglist.
Though I use and like Stack Overflow a lot, and though it does provide our users with lots of good answers, I still feel that SO splits the Mercurial community somewhat. In that way SO can be seen a harmful and counter-productive to the efforts of the people on the mailinglist. My questions are:
How have other projects dealt with this?
Can we do anything on SO to better tell users about the official support channels? I've already written something about it on the tag wiki, but I don't think it's seen by most people.
Maybe this is just a natural consequence of becoming a big project and so I should stop worrying :-)
From the discussion below, I've extracted the following great ideas on how to work towards integrating the two communities:
Add links to Stack Overflow in the project documentation
Make sure the Stack Overflow tag wiki point back to the project documentation
Create a script that periodically sends out an email with a list of unanswered questions