The block containing the transaction was mined by Eligius. The Eligius pool allows non standard transactions if the transation is relayed to it directly (plus a fee for the service I think).
They are accepted and valid in blocks though. So any miner can include them in their blocks. What Eligius, and some other pools do, is they allow accepting the transaction directly. So you connect your node to it directly and send the transaction as normal. It won't be relayed to other peers as they reject it. But those running a modified client will and can include it in a block.