We let things bake for a little while during the release of OmniGraffle 5.2.1 beta 2, we just wanted to make sure that there wasn't another shoe left to drop when running under Mac OS X 10.6 (Snow Leopard), and things are looking pretty good, so here's a release candidate for you all.
Peruse the historical release notes page, and find the release candidate at the not-so-properly-named beta page.