Considering the annoying brats with the bad language I've seen on the one or two times I've been in a Dawn of War lobby (never mind a game) then this is overdue, but according to Slashdot, Bungie are including a 'Mute the Jerk' button in Halo 3
I don't know if TGSC has experienced it in WoW (or if you even can - I've never played) but I'm sure most gamers will agree that muting the Squeakers is a good thing!
I wonder what other innovative ideas companies can come up with for online play?