PCMCIA Bluetooth
The card (and the only one I know of) is a 3Com Bluetooth card (v3 I believe). Can fetch the model number tonight if anyone is interested. There is an enabler you must run, call CardSuite I think, it then looks like a stock DBT-120 or Apple BT to the PowerBook. Worked in 10.3 and not sure about Tiger (have yet to install Tiger on Wallstreet).
Antenna is modular, can be inserted for no protrusion or ejected and raised for more coverage (not needed of course with Keyboard / Mice, etc).
Hope this helps.