Yeah, I'm wondering whether we should change that...  I don't
know what the policy on changing driver names is though, but
given that the driver isn't extensively used yet, we may be
able to.

I'd say

libertas_cs     for card-services cards (CF Cards, PCMCIA etc)
libertas_usb    for USB cards
libertas_sdio   for SDIO based cards

That makes the names orthogonal :-)