more or less a reality.
SprintPCS's TouchPoint phone supports data connections that were recently flipped on in almost all of Sprint (or should I say Worldcom) PCS's markets.
It's currently 14.4kbps, highly overpriced ($0.20/minute in packages, $0.39/minute a la carte), but still pretty cool.
I've not tried to configure it for Linux, but the manual includes support and directions for PalmOS, stating merely to hook it up via serial, and use the following modem preferences:
Modem - Standard
Speed - 14,400
Speaker - Off
Flow Ctl - Automatic
String - AT&FX4
Dial type - Touchtone
and program in your usual ISP's PPP settings and voila.
I'm pretty sure this would work equally well with Linux.