Bluetooth can be thought of as "wireless USB" and is a standard way of connecting a PDA to other PDA's, devices, and computers.  he Compact Flash format has been around for years and comes in two physical sizes. Type I cards are smaller, while Type II are slightly larger. Quotes are from the respective companies webpage and are not a value judgment of davespda.com.
 

Ambicom Air2Net BT2000 - Check Prices
"AmbiCom's Air2Net Bluetooth Wireless CompactFlash card is designed for mobility and seamless connections between your PDA and other Bluetooth devices. Certified by the Bluetooth Qualifications Board (BQB), our Bluetooth CompactFlash card complies with Bluetooth 1.1 Standards and enables the PDAs with Bluetooth Wireless connectivity."
www.ambicom.com

Belkin F8T020 - Check Prices
"Belkin brings you Bluetooth technology, the fast and simple way to wirelessly connect your computing devices together, eliminating the need for cables and physical connections between electronic devices."
www.belkin.com

Iogear GBC201 - Check Prices
"The IOGEAR Bluetooth Compact Flash Card for PDAs fits into both Type I and Type II CF slots on your PDA, and makes your PDA Bluetooth enabled. This unit complies with Bluetooth 1.1 specifications and provides you with a 723 Kbps date rate at ranges up to 66 feet."
www.iogear.com

Socket BL4508 - Check Prices

Feel free to email me about your own PDA, questions, comments, articles, rumors, and reviews.  I can be reached at dave@davespda.com.