Since I've received my G1, I also have been carrying around my Treo 680 simply because there is not yet enough Android software out to do all my SmartPhoning on my G1. I had been jockeying my SIM card between the Treo & G1. But every since T-mo switched me from the interim to the permanent G1 data plan, no longer am I able to use data services on my Treo. The Treo is able to place voice phone calls, but to web, mail, or ssh capabillity. Does anyone know if the new data plan is locked to phone model or IMEI (equip id num)? Is anyone else out there experiencing the same? If you have two G1's and switch the SIMs, does data still work? Does it work with your old GSM Blackberries?