The form factor would be very interesting. Having some kind of card implementation of wallet storage would be highly desireable. (At least, speaking for myself.) I would have to do more research on what would be required to get some kind of smartcard system going.
As far as form factor I thought fob would be more interesting at first in that there is not a need to cary a reader around when you want to use your wallet. That said the technical implementation is the same, it's a packaging question.There would be some technical changes necessary to things like the wallet file for example it would need to be able to contain references to private keys in addition to containing them but My goal with this thread was to gauge interest, and float price as part of that.
Heck, how about a bitcoin ATM that really is just a secure linux implementation that assigns coins to your card based on currency deposits?
As for the ATM thing, on the surface it seams that the transactions of Bitcoin transaction prevent their use in a ATM like transaction without an intermediary making some sort of guarantee on the transaction. I can of course imagine that longer term but it's only viable in this model if the technical infrastructure is put into place and people are wiling to pay
