
TweetDeck is really putting the pedal to the metal on the multi-stream, real-time web concept. I think they need to quickly change their name to something else otherwise people would always associate them with twitter.
With their announcement yesterday on support for Google Buzz, Foursquare and their existing support for Facebook, Linkedin, Myspace, and Twitter, they are by far the leader in this space.
They should build some analytics in to the service, where you can analyze in the real-time the effect of social media for an update across these streams. That would be really cool!