I'm in three groups, one of which I DM.
Eberron (my group) -- We'll be continuing the campaign with my very lightly house-ruled 3.5. After that ends (probably another year or so, bi-weekly), I'll be switching to Pathfinder or (much less likely, given my players) Mutants and Masterminds. I'm not exactly anti-4E (except for a couple of mindbogglingly stupid rules), but it's not the right game for me.
Age of Worms -- I can't say for sure, but my bet would be on us finishing out Age of Worms (probably about six months, bi-weekly), and then switching to Pathfinder Beta or SWSE. The DM of this game feels pretty much the same as I do about 4E; possibly more negative, but with less information.
Forgotten Realms -- I'm very unsure on this one. My best guess is that we'll finish out the campaign using 3.5, but I don't know how long that will take. (We're 11th level, but advancing slowly and without a set play schedule, and I'm not sure how far advanced in the campaign's plot(s).) I also don't know what the DM will do afterward; I'm pretty sure he's fairly pro-4E, but on the other hand I suspect switching games would lose him several players. On the other other hand, I'm not even sure he wants to or is planning to continue DMing.