What do you mean by "send unconfirmed transaction"? When you sign a transaction, it's always unconfirmed before it gets confirmed by a miner. This is not any different with Bitcoin Wallet.
The app can scan and relay raw transactions from QR code, if the transaction is relevant to your wallet.
I'm sorry, what I meant is that I want to be able to send a transaction using unconfirmed inputs. For example if I send funds from my offline computer (by signing offline and broadcasting the transaction from my online wallet) I want the option to spend them instantly instead of waiting for confirmation.
EDIT: Note in parenthesis added to clarify for poster below.