Text (UG+errata): 4/4. ; If ~this~ damages any player, choose an artifact, creature, or land you control. That player gains control of that artifact, creature, or land. [Oracle 2009/07/08]
They keep control of it until the end of the game (unless something else happens to it). [Barclay 1998/08/13]
All tournament formats have banned cards from Unglued.
