The WMP11 was Prism2.5-based until approximately September 2002 at which point it switched to Broadcom. As of this writing in the fall of 2002 there are no *nix drivers for BCM silicon though there is speculation that some exist and may be released at some point.
However, please beware that though this card used to be the favorite (no PCI 2.2 requirements like the DWL-520, is actually a minipci card in a carrier so can be removed for use in Soekris 4501) for use in HostAP systems, it no longer is feasible.
As of 11/9/02, the older Prism2.5 based card is still available (at Fry's anyway). The older card does not have a serial number on the box. The newer version (2.7) has a serial number on the box (currently starting with 727).