My nano screen is busted too, but like they all said, it's not work replacing, but it still works like a shuffle(I can still see the very bottom of the screen to shuffle songs), so I'm waiting on a nano update.
this is what happened to my friends screen it first only showed up a little and then when the whoile screen was filled they called apple and they sent him a new one.
there are plenty of people selling ipod duds on ebay.... ones that don't work. get one of those and pop your battery and harddrive in it... the battery and harddrive, as far as i can tell, are the parts that give out most often.