I didn't even tough on the race to the bottom effect the App Store might have, like on iOS. I don't want to see Mac apps for 99 cents.

I know it's just another store front in which to sell your software and the Apple cut can be compared to selling through retail where the store (including the Apple store) will want at least a 30% markup. My biggest worries are about what I've already mentioned, the licensing and how you can have the same piece of software in and outside of the store. And wether or not Apple has any stipulations about that as well.

A consumer purchasing your app directly in the past or in the future, might later discover the App Store and wonder why they're not getting notified of updates via that interface when your app is clearly listed there. I'm also worried about the approval process of course and that it might just lead people to stop searching via other channels for apps.

I'm going to have to go pay Apple $100 to find out more information about it...

Back on to Leopard... I like the new OS-approved way to do full screen apps. Making use of that in a number of designs won't be difficult at all and can really enhance the experience.