The final refund from The DAO due to the hack will commence tomorrow – see ExtraBalance Withdraw Contract to be Funded on September 15th.
See also my Ethereum.StackExchange.com Q&A – How do I get a refund for the amount I paid in excess of 1 ether to 100 The DAO tokens.
My extraBalance calculation was checked and reconciled against the independently generated results from @arachnid (Nick Johnson) and @lyricalpolymath (Beltran Berrocal).
More about The DAO, the hack and the refunds at The DAO 1.0 – The Bug And The Hack, The Refunds, Plus The Source Code And ABI.