T-Mobile will be selling the "Charm" device - or as they call it the '7100t' beginning this fall - possibly as soon as the last week of September. As is obvious now, it has bluetooth (for audio only, no "modem") - includes a *speakerphone* and is quad-band GSM. T-Mo will NOT be disabling the 850 band - in fact they are in testing with some GSM carriers now (including Dobson and Western Wireless) for 850 roaming.
No word yet on pricing. Maybe others have a better idea on that.