From The Consumerist:
"Reader Brad took his XBOX Live Gamertag to a friend's house. When he got home, he realized that he'd forgotten his memory card (with the Gamertag on it) at his friend's place.
He used the "recovery" service to get the tag back, but when he got access to his tag he realized that he could no longer use any of his saved games.
We are unable to comply with your request to provide a free Memory Unit. Accessories such as that may be purchased from a retail location."