We missed it on Friday afternoon, but apparently voice chat is coming in 2.2. Previously, we'd heard that Zul'Aman and guild banks weren't showing up until 2.3, but there wasn't official word on when voice chat was arriving. PTR players have reported seeing a voicechat interface, but of course it hasn't been hooked up to any code yet.
But Hortus now says we'll be seeing voice chat ingame sooner than we thought-- it will be coming soon to a PTR near you, and pending testing, should go live with 2.2. Wow. Blizzard must have done a lot of work on that behind the scenes, assuming that it is what they promise: a fully featured builtin voice chat client. Think it's coincidence that there have been a few sound bugs on the test realms lately?
Which means that at some point we'll have to ask this question: What will happen to Teamspeak and Ventrilo? There's a nice bit of industry there-- players pay for servers all over the place, and while each server is pretty cheap, altogether they add up to a nice chunk of change, I'm sure. My guess is that TS and Vent aren't going anywhere (because players are so used to them, and not just in WoW), but until we see what kind of interface Blizzard has created, we won't know if they're worth leaving or not. Seeing as it's the PTRs, we should get a chance to play with it soon.