Completely OT - soft WPA

So - i was just wondering, and I figured this is the place where I'm most likely to get responses.


Does anybody who has more than a passing knowledge of WPA know why it has to be implemented in firmware? Why isn't it possible to do soft-WPA a la winmodems? Is there any reason why a network card that thinks it's running in open mode can't be forwarding and receiving WPA-encrypted packets?

If it is possible to do soft WPA - does anybody know software that does it? (linux or windows - bonus points if it's windows)