(Not to steal anyone's thunder concerning a certain sought-after feature in some other application but…)
OmniGraffle 5.0.1 beta 1 is now available for download and it includes a very long list of bug fixes and the like. Much too long to go into depth here, but we've caught and knocked down the immediate and pressing issues that cropped up since the initial release of OmniGraffle 5.0.
A quick look on the horizon for further beta releases reveals more work in polishing up foreign language localizations, but for now please do download and check out the latest release.