I just read that article on the Android Developers Blog about Live Wallpapers.
The interesting fact in there – which many people might not know – are the possibilities what we developers can do with such live wallpapers. Just imagine you have a massive screen in the background of the phone desktop where you can do pretty much everything with. Kind of like a separate application, but the user will always see it behind his normal icons.
It is a very neat concept which you won’t find on the iPhone (afaik, you might want to correct me if I am wrong). Developers like you and me could show most recent stock info on there (check out Google Finance APIs), a list of the latest Google News or something else. You are only limited by your own imagination here. So hack attack and get freakin’ going!