I think my latest Twitter status sums up perfectly how I feel about this release. Ubercart 2.0-beta4 is indeed one heck of a release. We've had 80 commits since the beta 3 coming from 9 patch contributors, and I'd love to see those numbers continue to grow. People have reported and helped fix a variety of bugs all over Ubercart core, and we've improved the Conditional Actions support (and even gotten some more docs out!). Be on the lookout for changes to the cart block that make it easier to theme and compatible with page caching. Awesome. So, a big thanks again to all the users and contributors. I'm excited about the near future, as we aim for one more release (a release candidate?) before Drupalcon DC. We'll continue to ensure Conditional Actions is a usable replacement for Workflow-ng, and ideally we'll have a bunch of new contributors jump in to help provide better tax support in core. We're continually looking to bring in more eyes to review and help develop patches for Ubercart core. Check out our directory of issue tags for a simple way to find issues in our issue tracker that interest you. Grab it while it's hot. Test it. Abuse it. And let us know how she drives. Don't forget to backup before and run update.php after you've dropped in the beta4.
So... just realized I forgot a return value for an update function in the Auhtorize.Net module. If you have this enabled and see an error when you update, it's benign. The update function is simply a forward port from UC 1.0, and you can ignore the warning. Will be fixed ASAP.