I didn't know this, but apparently up until now European WoW players hadn't had voice chat activated. It has now, although with a few bugs.

With today’s patch (2.2.3) in addition to fixing some sound issues, Voice Chat has now been activated on all realms.

That's not an asteroid...
This just in: VC seems not to be fully functional on some realms. We're now aware of this and it's being looked into. 

WoW Insider ran a poll about the roll out of voice chat on the realms... the results are pretty much to be expected.

Earlier this week, voice chat was rolled out to all of the US realms that didn't yet have it active -- meaning that by now, all of us should have access to in-game voice chat without the bother of any 3rd party programs. However, the rollout was a bit shaky, with numerous players suggesting it was causing unplayable lag. We asked our readers what their experience had been with voice chat, and while 25% clearly experienced some trouble with the system, an astounding 40% just don't care about the feature. I have to admit -- I'm in that camp as well. While voice chat is a handy feature to have, World of Warcraft has been on the market for a while now and everyone who was interested in voice chat has become accustomed to those 3rd party solutions.

Voice chat is now live on all servers:

The Voice Chat feature is now active on all realms. Players will need to go into the Options menu under Sound & Voice to activate it. We look forward to hearing you in game!

Want to know what the new voice chat is like, but you aren't on the PTR? Never fear... WoW Insider have come to the rescue with a hands on review of it. Is it better than Vent, is it annoying, does it work well?

Unfortunately, it's complicated enough that it probably won't be extremely widespread-- players who haven't found the need to join up on voice chat yet probably still won't feel a need to do so. But for guilds who don't want to pay for a separate server and friends who group together often, the ingame voice chat should work just fine.

Some people have apparently been having problems using USB headsets in World of Warcraft voice chat. Here's the proper steps though:

1. Plug in headset before loading WoW.
2. Load WoW.
3. Select USB Headset for voice in/out and/or audio out (choose what you want for your outputs).
4. Reboot WoW, and it will work (It even says you ahve to reload WoW to have these changes occur)

Here's the official Blizzard FAQ that was posted in the forums regarding the new Voice Chat:

Q: What is the new voice chat feature in World of Warcraft?
A: The voice chat feature is the proprietary in-game voice communication system for World of Warcraft. It allows World of Warcraft players to communicate with each other using a simple-to-use interface that is seamlessly integrated with the game.

Q: Is the voice chat feature free?
A: There is no additional charge to use the voice chat feature; it is included with your monthly subscription fee.

Q: How does the voice chat feature work?
A: The voice chat feature is fully integrated within World of Warcraft. You can enable voice chat by accessing the sound options screen and turning it on. When enabled, it can be configured to transmit your voice either whenever you speak or only while you hold down a button. You can also use it to listen to other players without transmitting your own voice.

Q: Can I speak in more than one channel at a time?
A: While you can join multiple chat channels, you can only have voice chat enabled in one channel at a time. You can switch voice chat between channels by using the new chat interface found in the social window, or by clicking on the voice chat options button located near the mini-map.

Q: Why did you choose to implement voice chat?
A: Since launching World of Warcraft, we have made a number of improvements to the interface to offer players more convenience and ease of use. The voice chat system is another such feature. It is simple to use and fully integrated into World of Warcraft, making it that much easier for players to communicate with each other.

Q: Can I still use third-party voice chat programs with World of Warcraft?
A: Yes, you can still use third-party voice chat programs while the integrated voice chat is disabled. However, World of Warcraft’s voice chat feature allows you to use a simple system built into the game’s user interface rather than toggling between multiple programs. Additionally, the voice chat feature in World of Warcraft displays who is speaking at any given time directly in the game interface.

Q: Will I be able to customize voice chat through World of Warcraft, or is it accessed via the account management webpage?
A: You can access the voice chat options via the in-game options menu. The parental control options of the voice chat feature are accessible via the parental control system located on the official World of Warcraft website.

The LFG chat channel is coming back, albeit with a few changes and requirements...

We're making many improvements to the Looking For Group tool, most of which are still in production and can't yet be discussed. Player suggestions and feedback are playing a large part in the changes we're making and we want to emphasize that we are indeed making improvements.

The change we can talk about right now is indeed the return of the looking for group channel in the next major content patch. With it comes a rather significant requirement, and that is that you will have to be in the LFG system set to looking for a group or looking for more to see and use the channel. The global LFG channel will only be viewable and available for use to players while they are in the LFG system.

We hope to see the combination of the LFG tool coupled with the ease of use of a global channel help to improve the LFG tool and players use of the tool. Again we're making other improvements based on feedback and suggestions which we'll be able to discuss in the near future.