The upcoming App store for Mac seems to have the internet in a mini-uproar. There seems to be a general fear that this is the narrow point of the wedge. That Apple's long term plan is to lock-down the Mac, the same way they have locked down the iPhone and iPad. And yes, that could be their end goal, but I can't help but wonder if maybe a desktop app store couldn't lead to more-open app stores across the board.
Limiting the app ecosystem makes sense for a phone. By it's very nature, its a limited device. It's OK if it can't do everything--as long as it lets me accomplish useful tasks while I'm on the run. On the other hand, users expect to get more work done on their iPads. Not surprisingly, the iOS SDK loosened up considerably with the iPad's release. Before, each application was kept entirely in its own sandbox. Now we can move files from one app to the next. It may not be complete access to the file system, but it has vastly improved the iPad's usefulness.
Soon we will have a full-blown desktop app store. Most of the excused given for limiting apps simply don't apply. We're no longer dealing with devices that have severely limited resources. We no longer need to worry about upsetting AT&T. Users don't need to jail break their computers to load applications from outside the app store. Most importantly, users will have even higher expectations on what applications can and should be able to do. This will create a considerable amount of pressure on Apple to open up the process, and despite what many people think, Apple is not immune to pressure.
In many ways, Apple is already on a slow path towards loosening restrictions on the iOS app store. They've lifted the ban on third-party languages. They've published a more specific list of their requirements. They continually add new features to the SDK that allow access to previously restricted features on iOS devices. I fully expect this trend will continue as Apple feels their way through what is obviously a tricky and difficult issue. I also expect this trend will accelerate once we have a desktop App store. It won't happen overnight, and it won't be perfect. But, I have a feeling that the Mac App Store will be a good thing for the larger App ecosystem.