But it turns out the huge volume is from this transaction http://blockchain.info/tx-index/11999735 which looks suspicously like it could be from the latest Bitcoinica hack. I don't know if the Bitcoinica hacker was using a My Wallet account or just choose to relay the transaction through our server but it is interesting none the less. Btw as far as i'm aware none of these funds were sent through the mixer.