I want one quite a bit. Yet, the upgrade path from the 3GS seems unclear (if at all existant). Unfortunately it seems that you have to skip every other iPhone

I want one quite a bit. Yet, the upgrade path from the 3GS seems unclear (if at all existant). Unfortunately it seems that you have to skip every other iPhone if you want to keep with AT&T's discounts since they come out with one every year. I'm not eligible to upgrade until 3/2011.