The Sony Ericsson T616 has a Bluetooth adapter that acts like a serial port. If you put the phone in serial mode, it understands a wide range of AT commands. Some useful references: R320s_WP_R1A.pdf, 888_r1d.pdf, AT Test commands, Google search for [CPBR ericsson].
I hope to use this to modify my contact list
at+cpbr=1I bet floAt's Mobile Agent uses this protocol. Other folks have hacked their phones to be remote controls (Python, Perl). Phonefront is a commercial control app.