Does it store the entire blockchain on the mobile device, or have you figured out a way to program a "lite" wallet?
It doesn't store any of the blockchain. It is not a Bitcoin client itself, simply a frontend for Instawallet.
Ahhh, ok. Still, that's neat, and that gets the ball rolling on mobile wallets, which are desperately needed!
I'm not sure what sort of 2D barcode format you are currently using, but why not simply adopt the now-standard QR code?