Microsoft warns against Xbox Live Sharing, Part II
by icebergstorm on Comments
... and I think Larry speaks about sharing "account" with "friends" to unlock gamerpoints, more than to your family member (I mean if your brother/sister can do it, why ask your friends, right?), beside are they gonna start tagging electronic device to every single online gamer (including member of your family playing online?) ... I don't think so :P