Here’s a short article and another one (with some links) about the new integrated voice feature in WoW.
And some responses from the wow forums.
Here’s another short article about it.
One of the more coherent threads from the wow forums on the topic is here…
And one of the more succinct is here

Because there’s a long history of using voice in WoW in particular situations (raids, end game instances) rather than across the game as a whole, I’d not assume that the arrival of the integrated voice feature (2.2?) will resemble the arrival of the voice feature in SL…but familar issues are being discussed at the forums. There’s concern that it will ruin the game, ruin the ‘immersion’; that voice will mean lots of people yelling drivel/abuse, and there’s the assumption that ‘if you dont use voice it’s because you’re a man playing a woman character’ (behind every sexy-lady night elf etc. etc.). I’ve not found posts that talk about how the voice feature might be differently employed on RP servers (compared to PVE or PVP servers) but it would seem at least a possibility. Maybe.