Apple hasn't shipped the PCCard family for IOKit to develoeprs yet. (At least, not in general). One of the software development managers for WCND at Lucent posted on the Darwin Developers mailing list back in Sept. that he was very interested in creating support under Mac OS X Public Beta, however, Apple hasn't supplied what he needs yet.
Any and all PC Card drivers for Mac OS X are most likely being held up until Apple ships an update to IOKit that includes PC card support.
You can read the relevant messages on Apple's mailing list archives for the Darwin Development mailing list.