Hugo Weaving (Agent Smith) may be playing the voice of Megatron in Micheal Bay's upcoming Transformers film adaptation, but he won't voice him in the game. Normally a cast change for a movie-based game is a bad thing, but this change may actually please fans.
Frank Welker, who voiced Megatron in the original animated series will reprise the role for the game. This means that the game will have the original voices for both Optimus Prime and Megatron. Activision has said that the reason for the voice change was to please Transformers fans. While I don't doubt that motive, I'm sure they saved a few pennies by using Welker instead of Weaving.