i'm curious about this as well. I just got my new iPhone 4 and transfered all apps via iTunes, but my EPSN World Cup app that i upgraded to the full version (it's an in-app upgrade) doesn't seem to recognize that i've already purchased the upgrade on the old phone and wants me to buy it again.
if i "purchase" the upgrade again, i'm wondering if it will say "you already have downloaded this app and will not be charged" like it sometimes says when you update paid apps.
can anyone verify this?