Also comitted a proposal for the QR code format: https://github.com/ovidiusoft/bitcoin-scripts/blob/master/PaperCoins/QR-code-format.txt

If includes the URL field proposed by casascius, and a few others. Don't take it as a full proposal, it's basically just a bunch of random ideas, with the only intention of starting a discussion. I'll post some scripts that produce the new QR codes soon.

So, waiting for your comments. As I said, I would love to get the attention of POS/client developers.