TweetDeck, took a quantum leap in real-time updating on Friday, introducing version 0.36.1.
Yes, TweetDeck now updates in Real Time ... which they readily recognize "may be a little overwhelming".
TweetDeck is one of those apps that has been improving steadily since it's introduction. The new real-time feature can be throttled making it easier to get used to. Other new features have also been added.
In addition, previous releases have added Facebook, MySpace, LinkedIn, Google Buzz, and Foursquare (Yes, you CAN post to Foursquare from your desktop. I'm not sure why you'd want to, but you can :)
Other versions of TweetDeck support iPhone, iPad, and Android.
The latest hyper-active desktop version of TweetDeck is powered be the latest version of Adobe's Air cross platform engine, version 2.5 and can be downloaded free here.
Warning. If you follow as many people as I do, You WILL be overwhelmed ... but that's part of the fun .. and there are some tips and help (to calm any fear?) here.