That's interesting. But consider making it a Bitcoin ready multipayment device. Let's say you can store credentials for credit/debit cards, with all kinds of fancy features that justify the price of the device, but that it so happens to be able to store Bitcoin transaction keys and the means to use them in a transaction with security appropriate for carrying around daily spending amounts. It could provide a back-door for Bitcoin spending from a device that people are already carrying around.
It is one thing to provide enough support for doing a transaction through a reader. Maybe this is setting the bar a little high, but what if there were a way to transfer between Bitcoin and other payment methods right on the card? Let's say you are where you can only pay with a Visa/MC but most of your funds are in BTC. You could make a transfer on the card from BTC to a Visa/MC balance and then make your pruchase. The merchant doesn't even need to know anything about Bitcoin. Perhaps it could be as seamless as a single transaction...
I don't disagree one however requires much more technical and business work than the other and while it would enable new scenarios in the mean time the platform risks still remain.
It may turn out that there is insufficient interest to justify even the most basic project which would still be a significant financial investment if one was to make it scale to the community in an economical and usable way.
My thinking was crawl, walk, run.
Get the keys and wallet-into a crypto device, move much of the client into such a device, build pos infrastructure and account scenarios.... You get the idea....
I should add that at least for us users it's trivial to encode the credit card data into a mag stripe on the back of the card but the issuers would through a hissy fit; in the eu this would be very problematic for technological reasons also.