The 30% margin that Apple is asking here seems comparable to the retail margin that exists with standard physical retail channels that Microsoft and Adobe both participate heavily in. Add in that Apple is taking care of the servers/bandwidth, credit card transactions and provides a place for the apps to be found and it seems to be a good place for Adobe and Microsoft to have their software. Additionally, I have to wonder if Apple is placing any anti-piracy measures in there on top of whatever the developers currently have in place. In short, I think Adobe and Microsoft would be unsure to not participate in their App Store, otherwise they have the possibility of The Gimp being the #1 image editor over Photoshop in the rankings.