Yes, the waterproofing issue for PDA's is being addressed too I think. There was discussion about this on
www.ugser.com in the forums section on GPS.
I know its a BMW site but those guys are mad on GPS so just about every eventuality gets discussed
Must say i fancy a Gramin iQue (a Palm PDA basically) and RAM do a mount but as yet no waterproofing I think (which must result in a different mount I guess).