Today, Iain Dodsworth rolled out an update to the service with some much-requested features, including the ability to alter the application's look and feel, an improved user interface, support for new URL shorteniing services, part of the never-ending battle to be verbose within 140 characters or less, and additional security, as calls to Twitter are now made using HTTPS.
TweetDeck Shows Tweets, Groups, Replies, Search and DMs in One Window
The new update allows you pretty much all the functionality you get from Twitter's Web site from within TweetDeck, including marking and unmarking individual tweets as favorites, and adding the ability to follow or unfollow other users. Combined with TweetDeck's integrated search capability, the pair would set you up to follow a group of users who are focused on topics you're interested in.
You can see Tweets and Replies flow by in their own columns
And should you want to avoid being overloaded by seeing all the tweets from your friends scrolling by, you can even "turn off twitter updates", letting you use the tool as a desktop Twitter search application or a TwitScoop client. (See the full release notes here)
So far, I've trended toward using Posty, as it puts my updates on both Twitter and Identica, but when it comes to strictly Twitter, TweetDeck's UI and feature set puts the others to shame. You can get TweetDeck yourself at http://www.tweetdeck.com/beta/.