The long-awaited TweetDeck beta (or pre-beta) that we knew was coming this week got leaked online today, after someone very diligent found a direct link to it on TweetDeck's own site. The link is no longer working, but not without a bunch of people grabbing a copy first and uploading it to a multitude of mirror sites.
I had the pleasure of demoing an early version of the software at Google I/O and was highly impressed. I do believe TweetDeck has a very good chance to become the best Social client on Android.
Remember: this is a beta, a pre-beta even, so it will be buggy.