I don't have a 770, but I've been using bluetooth with T-Mobile (GPRS) now for several years (they've got unlimited data for $19.99) on a variety of hardware.

In my area, the only real options I'd consider are Cingular or T-Mobile; and Cingular is supposed to offer higher-speed data (though T-Mobile has something in the works).

The only problem I've had is the speed - it's low-end dialup at best. Though I once did a webcam chat to Switzerland from a dive bar ;-)

I think the 770 will be a great display device for my Motorola v3.

Brad.