I've been wondering about this. So, when I receive my new iPhone 4, I am assuming that it will have the new micro sim already installed in the phone. I won't just be able to pop my old regular sim into it. I'm thinking that I will go to iTunes to setup the new iPhone 4 and do all of the rate plan setup and somewhere along the way it will transfer my current phone number to my new iPhone 4's micro sim. Do you guys think this is the way it'll work? A drawback to this new micro sim thing is that I no longer will be able to swap the sim from my iPhone 4 to any old phone that i may wish to use for whatever reason. But I'm thinking that there will be adapters that will work just fine, so that won't really be a problem. Just throwing this out there.