Yes, Iron Man had some seriously impressive effects. But Benjamin Button, for any other problems it had, had some impressive effects.
It's one thing to make robots or aliens or whatever look "real," but it's something entirely different to completely generate an actors face and place it on another actors body and have it look completely seamless. This video, which shows some behind-the-scenes footage of how they took Brad Pitt's face and placed it, aged up, on a smaller actor's body. While Iron Man might seem like the natural choice for Best Visual Effects at the Oscars, Benjamin Button is the film that used the most impressive effects. I'll take realism over flashiness any day of the week. [Rope of Silicon via io9]