The most recent beta release to OmniGraffle won't have a great deal immediately visible to the user; instead we've incorporated a number of under the hood changes to how our software update mechanism works to bring it more in line with other applications we have such as OmniFocus.
Hopefully this integration has gone smoothly, however if bumps in the road appear, don't hesitate to contact us.
OmniGraffle beta release download page.
Historical release notes.