2 cards I know work from personal experience:
SMC EZ Connect 11Mbps Wireless CF Card
Model No: SMC2642W
Linksys Wireless CompactFlash Card 2.4GHz 802.11b
Model No: WCF12
I've been using the SMC EZ connect since OZ 3.2 or so. Never had to mess with any configurations. I just plugged it in and it worked. I got the Linksys card (actually arrived today) because the SMC card is kind of falling apart. The back is coming unglued and it doesn't always detect correctly any more. I *have* subjected it to about a year of abuse, carrying ot around in my pocket almost constantly, inserting/removing from the Zaurus multiple times every day. The Linksys feels a little more solidly constructed to me (and it looks nicer). When it arrived today I took out the SMC, plugged in the Linksys and OZ just brought the interface right back up. No configuration changes at all. HTH.
-John