Wow, this brought Plasma Burn out of a Cave. Wrote a little blurb on this. Im seeing more and more games adding sometime of Social Networking to there games. Microsoft is working on there own Social Networking Platform called Spaces. And its tied to your XBOX live account as well. Alot of options here.
But Yea check this out if you Play WoW, and would like to Tweet a bit
Video included.
http://www.plasmaburn.net/2009/07/05/twitter-from-inside-world-of-warcraft/