As previewed before, the Blizzard developers made mention that they were working on an in-game voice-over-IP system. Well, "Games for Windows" magazine has an article that confirms that Blizzard will be implementing this feature in the future. While the release of this feature has not been scheduled, more specific information and details of the system have been discussed.
Some of the features that have been disclosed include feature that lights up the speaking character's name in the interface, allowing you to actively see who is speaking, and target them if necessary. Also, the voice channels can be separated so that the music can be silenced while a player speaks, or the music can be over normal speakers and voice can be sent directly to a headset.
While the replies of the players are mixed as to the potential of abuse, options of use, and how it will effect gameplay and system lag, I think that this will be a feature that could be amazing if done well. I can't wait to give it a try!
You can read the article here.