I think Steam know exactly what is going on with the gift packs. No one in their right mind is going to buy 6 copies of splinter cell and then give them away. As long as people are doing this in a non-profit manner steam wont mind. Sure they have mechanisms in place etc
Maybe but it is explicitly against their rules, I wouldn't risk my account. So long as those involved in this know the risks.
Another thread on it here: http://forums.steampowered.com/forums/showthread.php?t=1612527