Some time passes, some code gets written, some bugs (quite a few, in fact) get fixed. This particular release zeroes in on a number of Visio import and export support fixes, direct import of PDF files has been greatly improved, and a large number of issues surrounding groups and tables have been addressed.
Just a little backstory here concerning groups, particularly those special groups in OmniGraffle that we call tables. Way back in the day when the table feature was first implemented, a number of neato features were present that over time in testing proved to be rather problematic, so they were either removed or obscured. In going over a number of group-related fixes, we've managed to address those problems, so with this release you can do some pretty neat things, including rotating tables as well as rotating individual table cells. Give it a try and see what you think.
Alongside bugs and issues with groups are a number of stability fixes in place that relate to moving and rotating groups with lines connected within, so if you've been running into a large number of cryptic crashes, you will want to take a look at this beta release.
The beta page has returned, and the historical release notes remain in the same location.