(There may be other possibilities that I have not thought of).
It is possible the recipient was using mtgox to receive the funds, and mtgox was having issues again lol.
Anyway, if OP checks blockchain.info (or the other sites I posted) and finds the tx confirmed, then it is pretty much the recipient's responsibility to fix problem on his end.
Yup. So unless he gave you his address wrong, which is his fault, or you typed it in incorrectly, then he must've recieved the funds, and if not, it's his fault.