I did a little poking around for you. According to SocketCom's compatibility grid, the Treo 650 can use their
Secure Digital Scan Card which is a different product than the
SDIO Scan Card 3M which is
not compatible with the Treo 650, and possibly the one you bought. Darn similar-looking though, aren't they?
A word of caution: the Treo 650 has very limited SDIO support. You'll definitely want to save your receipt if you buy the other card. Either way, the tech support you'd have to call would be Socket's, not Palm's.
Good luck.
-K