Is there any market for iPhone-style apps on OS X?

Many of the apps on the iPhone are clients for websites. Facebook, Twitter, MySpace, Yahoo!, Google, the list goes on and on. What’s great about these applications is that no data is stored on the iPhone, it’s all synced up to “the cloud.” When you move to your computer or another device, all your changes are already there. Would there be a market for such apps on the computer in general?