I am working those days on a POS system for ipad which focuses in the ability to print bills in a closed network with a local wifi printer (No internet connection needed).

Basically the app works in 2 modes :
- With an advanced wifi printer which can setup an ad hoc wifi network
- With a common wifi printer and an Airport Express to setup an ad hoc wifi network.

The final goal is to be able to go anywhere with a printer and an ipad, generate bills and print them directly. For exemple, it could be very nice for showrooms salers, what do you think ?