I'm currently in three games.
One I joined in 1987, and has predominantly the same cast.
One I started running back when 3.0 just came out - we were doing character creation before the MM had been released. Bysides myself, it only has a single player overlap with the first game. We have one new member who's been with us for well over a year and a waiting list to get in.
Last game I'm in started only a few months back, but it's entirely people from the first two groups so I don't know if that counts as "a new gaming group".
Cheers,
=Blue