Epic and Valve have just now enabled the ability for UT3 Retail keys to be registered on Steam. This will allow owners of the retail game to enter their keys into Steam and download/install the game through Valve's service. To take advantage of this, simply open Steam, go to the 'Games' menu, and select 'Activate a product on Steam'. Enter your UT3 CD-Key and the game will appear in your Steam 'My Games' Tab.
Let me be the first to say: YEEEEESSSSSSS!!!!!
Let me be the first to say: YEEEEESSSSSSS!!!!!