I currently have a 3GS and my wife has the 3G. My eligibility to upgrade doesn't reset until December (double checked ), but my wife is eligible to upgrade now. I was thinking of buying the new iPhone under her account (with the eligible upgrade with a new 2 year contract) and then swapping the SIM card from my 3GS and the new 4th Gen iPhone. I had asked an AT&T representative last year about swapping the SIM card between a 3GS and a 3G and they indicated that it wouldn't be an issue. However, my understanding is that the new iPhone will use a micro-SIM card. I assume that AT&T can still help me swap SIM cards between our 2 iphones, but I'm not sure. I thought I'd ask the experts on MacRumors. Does anyone have any idea whether this will work or not? Thanks for your help!