We're sticking with 3.5 for now and the foreseeable future...by which I mean probably until 5Ed and beyond. In a group of 10+ gamers, only 2 people have expressed an interest in trying 4Ed- neither wants to DM it. I'd play the game, too, but since I'm the one with the books and will NEVER run it (yes, I dislike it that much), we're at an impasse.
Personally, I may try to run a campaign I'm designing in True20 or M&M (with an announced but as-yet unreleased fantasy genre supplement"), since one of the features of the campaign is that the players will be designing their own spells & magical effects...
Otherwise, I'll just run it in 3.X (IOW, 3.5 with stuff brought in from 3PP products).