Add former Republican presidential candidate John McCain to the 40-plus lawmakers who "tweet" on Twitter. We just got news that he's pumping his daily activities into his BlackBerry. Follow his tweets here. Interesting thing about McCain is that he doesn't just use the social networking site to post official business. He also tweets about other stuff like promoting the Arizona Cardinals in the upcoming Superbowl.
Speaking of tweets, you can also get regular updates from Whispers on Twitter.