Great idea. I just ordered some cards.
As a guarantee of the security of your cards, will you, at some point in time, compensate for bitcoins that were withdrawn from addresses of cards that were not tampered with? :-)
In the exceedingly rare case that you open a card and find that it does not have value (or you find a counterfeit), PLEASE let me know; I'd like you to send it to me for investigation. If I believe you (and I probably will), I will reimburse you the value of the card. Also, I have a 50 btc reward out if anybody can demonstrate a method for surreptitiously accessing the private key.
This is so cool, I'm ordering one of each right now!
I only wish you didn't use MyBitcoin. I've had payments eaten by their service before when my transaction did not get broadcast before the payment address was reused. So I'm transferring the amount to MyBitcoin and then paying directly with my account.

I'm considering writing custom payment processing. An order status page confirmation system is also in the works.
After production scales in the next week or so, I'll begin talking to people who are interested in buying in bulk, selling on commission, reselling, etc. In the slightly longer term, there are also some new products in the works!
UPATE ON SHIPPING:
Thanks to everyone who bought cards. I'm on track to mail the cards out WEDNESDAY. Sorry for the brief delay. Once production scales, cards will be sent more promptly. I'll definitely keep you all updated on your order status!