GSM seems nice, but Cingular has never been a good company to work with and shows no signs of improving. I have had to call the PUC on them multiple times for overcharging me as much as $400 and refusing to refund it - in the end, after intervention, they did. Their customer service is surly-polite, if you know what I mean. Getting to a live person is an exercise in patience, the phone menu is practically never ending. So, I will hold off till they have a CDMA version that works with Verizon - and, no I am not a giant fan of Verizon, but compared to Cingular, there is no contest.
On a different note, if in fact Safari on the iPhone *IS* Safari (did Steve "mislead us" when he said it was the same Safari as on Desktops?), then you have an application platform built in - Safari supports a plenty rich DHTML/AJAX model that allows for Widgets and other web based apps. Think "Web2.0" and the iPhone makes a lot more sense as an edge-unit in that arena.