An interesting piece at 1Up talks about the effects of closing down an under-performing MMO, both on the players and the developers. Getting the "don't look back in anger" treatment are Cyan Worlds's Uru Live and NCsoft's Auto Assault. Containing snippets of quotes from the creators of both games, there are lessons here for upcoming MMO devs that should be heeded.
Interestingly, there is mention of an indie MMO being developed by some of the Auto Assault team called Apokalypsos, apparently featuring a post-apocalyptic setting. Combining FPS gameplay with vehicular combat, this sounds like Mad Max for the massively multiplayer crowd. We'll keep an eye open for further developments.