Something weird has happened.
Yesterday, someone came over to buy some Bitcoins.  We accepted his cash and sent him his Bitcoins.   Ed sent them by making a Withdrawal from his own MtGox account TO this person's Bitcoin address.  
Unfortunately, this young man sat here with his laptop and his Bitcoin client open... and they never showed up.
Hours Later, they still hadn't shown up.
I emailed MtGox.   MtGox promptly replied showing me that the transaction IS IN the block chain.  
However.... still no sign of it in the Bitcoin client.
We verified the Bitcoin address from his Bitcoin client app and it matches perfectly.
How could this happen?