> The app store model in iOS, Android, Mac OS X Lion, and Windows 8 is not the same as the Linux distro repository model
It's only different in policy not technology.
I could create an source for Debian and a web site where third parties could upload packages. I'd just say "By policy you may not depend on any package" or perhaps "on any package not present in release foo." Anyone who adds this apt source can go to his package manager and get third party apps, any third party who wants to can go to my web site and upload his apps. There's no dependency management because the packages simply don't request any. The only thing missing is a mechanism for paying for the apps.