gCalWall
Here we see an app with enormous potential, which has been unfortunately crippled by the limtations of the iPhone SDK.
gCalWall aims to create a ‘today’ screen for the iPhone like those found in Windows Mobile devices. As the SDK doesn’t let apps run in the background, you have to open the app to update the home screen. As the SDK doesn’t let apps change the wallpaper, you have to manually set it once it’s generated. And as the SDK doesn’t let apps access the calendar, you have to use Google Calendar so your appointments would be pulled from there.
Hopefully the SDK will give more capabilities to applications at some point so apps like this could become meaningful.