Yep, it's a double-edged sword. The App Store may offer things like the iCloud SDK but will restrict apps from using features that compete with Apples own apps

Yep, it's a double-edged sword. The App Store may offer things like the iCloud SDK but will restrict apps from using features that compete with Apples own apps, as well as any cool hacks which apps outside the App Store are free to make use of. My take is that Apple is herding developers into the App Store, enticing them with SDK features and the promise of riches, and at some point they will change the default gatekeeper setting so that users see great big warning signs and are too scared of running non App Store software. We're probably still a few years away from this happening, but the writing is on the wall.