Dang it, there are already PSN games I'd buy, but they need to let you DEAUTHORIZE HARDWARE so that other hardware can get authorized! I know they let you use it on 5 systems, but there's still SOME chance you could use all those up.
I'd rather it just be one system at a time, but you can go into a menu to deauthorize it, then authorize it on another system (internet connection only required during that step).