Beta-8 is now available for download! This release includes a completely new user interface, along with substantial new features and capabilities. Although an actual change log is not listed I have been an ubertwitter user for quite some time and using the new release most of the day.
I can honestly say that this update is just like the past updates, "they made it even better". OTA link provided below.
Beta-8 can be downloaded here via OTA : http://www.ubertwitter.com/bb/download.php