It should come as no surprise to anyone that the Omni Group has jumped aboard the Mac App Store train. Omni has long been a popular creator of Mac applications and has done pretty well for itself with the iOS apps that it has already released, with more on the way. On the day after the Back to the Mac event, Omni Group CEO Ken Case tweeted that the Mac OS X versions of all five of the company's Mac apps will also be available on the Mac App Store.
That group includes the ever popular OmniOutliner, plus OmniFocus, OmniGraffle, OmniGraphSketcher, and OmniPlan. OmniFocus and OmniGraffle are already available for the iPad, with OmniGraphSketcher and the others promised soon.
In all likelihood the vast majority of Mac developers will move into the App Store, with the likely exceptions of Adobe and Microsoft. For most developers, having an outlet built into the OS and avoiding the hassles of payment systems just seems like too good a deal to pass up.