Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. (It can attack andthis turn.)
10/1/2009 Act of Treason can target any creature, even one that’s untapped or one you already control.
8/15/2010 Gaining control of a creature doesn’t cause you to gain control of any Auras or Equipment attached to it.
7/1/2013 If you control a legendary creature and gain control of another legendary creature with the same name, you’ll choose one to remain on the battlefield and put the other into its owner’s graveyard.