Nizam pointed this out today. Its a nice idea but only uses the bluetooth ftp profile, so streaming wont work I believe.
HOPBIT is a personal mobile server that combines the wireless connectivity of Bluetooth with the storage capabilities of a large capacity hard disk drive. Small enough to slip into a pocket and light enough to carry everywhere, HOPBIT is a powerful personal tool that can transmit, receive and store large volume data sources–including images and music–communicate with digital networks, and provide a new dimension in portable memory for personal information equipment, such as PDA and PC.