I have first-hand experience of being upgraded on an award ticket, and I remember a thread awhile back in which an number of others (Plats. mostly) indicated they had been upgraded too.
I seem to recall that people think this is not an "official" policy, but it seems to happen with some frequency. In my case, I didn't even asked to be upgraded--they did it for me and my wife at the gate (both of us on award tickets). Good luck.