Ouch Rp3, did if float to the bottom of your backpack? I'm a little concerned when I travel with mine and tend to put it screen facing some hard flat object to avoid just this kind of occurence. I broke a PDA screen once on my iPaq, but was able to purchase a replacement for ~$90 and replaced it myself. Too bad there aren't any readily available eInk screens available so we can do this ourselves.
Sorry to hear about this. Please try to be more careful, hope this doesn't happen to you again (or me, for that matter).