Interesting Idea.

Things it needs:

1) A browse feature, so you can see other peoples screens

2) A mobile optimized homepage, so using it from the iPhone is more attractive.

3) A reminder of how to take a screenshot on an iPhone :)

4) A better way of handling "non-apps", both folders and mobile-optimized sites on my home screen confused it.

5) Perhaps a recommendation engine for new apps based on the apps on the screen.