Just upgraded! Paid for next day shipping as well. Not sure about the memory size but I'm guessing it's the 16GB. I didn't see another option. Can't wait!
BTW, it sais that it's not available but I'm guessing it's because the system isn't fully updated yet.
Just ordered mine from tmobile over the phone. Unfortunately it's already back ordered. It's scheduled to ship on the 26th. I think I may run to the store here in a little bit and just get one there if they have one though.