The new version includes several new features and bug fixes surrounding URL-shortening (tinyarro.ws now supported), 32-bit stability, and improved Growl notification support. Other new features include three-finger "back" swiping on supported trackpads, drag-and-drop video support, as well as the ability to record and tweet videos from your iSight using ImageShack's yfrog image hosting service.
Our own Michael Rose was so excited about the update that he promptly downloaded the new version. Take a look at this excellent (and very brief) video he posted using Tweetie 1.2 for Mac. After (or before) you check out Mike's shirt of the day, head on over to atebits and grab the latest version of Tweetie. Also, be sure to tweet some videos and mention @TUAW and @atebits so we can take a peek -- but don't let the ease of posting videos steal your soul.