Offline payments with Android wallet This Android application for Bitcoin wallet, claims offline payment as a feature. It says, 


  When you're offline, you can still pay via Bluetooth.


A payment is concluded only when the transaction is broadcast to the network and confirmations are made for the transaction in a certain block as mined. So, how does one "pay" via Bluetooth?
You can simply send the signed transaction to the other entity (e.g. via Bluetooth) who then can send it to the Bitcoin network. The transaction doesn't need to be sent to the Bitcoin network by you, it just needs to somehow get to a miner to be included in a block. Even if you print it out, send someone a letter via snail mail, they type it in, and send it to the Bitcoin network, it'll still work.