When I first activated it, I got a message saying to contact AT&T to turn it on, but I clicked the tethering icon again and it allowed me to turn it on and off, most likely because AT&T hasn't made a plan for the iPhone yet. I'm not entirely sure on this subject, but when you pay the $30 or so dollars to AT&T, they allow you to turn that switch on, otherwise you get the message to contact AT&T, right? But many of us will already have this tethering icon activated to the point where we can turn it on and off. So if you use tethering on your laptop when they come out with a plan, will they just bill the $30 to your account? And who here will download the new carrier settings/OS if it disables this ability to activate tethering? Will this all depend on AT&T's ability to know which phone is tethering?