Ok today I got my iPhone 4 I'm going on vacation and am going to have AT&T deactivate my iPhone 4 and reactivate my 3GS only because I have mywi on my 3GS and want to be able to tether to my laptop while I'm away AT&T said I don't need to bring the 3GS in I can just cone by and pickup the new activated sim for the 3GS so when I put the sim back into the 3GS am I going to lose my jailbreak? Is it going to make me connect to iTunes and update to 4.0?? Or will it be like nothing ever changed??