Bioware has confirmed that the PC release of Mass Effect 3 will not be supporting controllers. Instead, players will have to rely upon mouse and keyboard controls to take Shepard on the final strech of his journey.
But then again...they did only say that they're not supported. So they may still work. Maybe. But considering that players still have a little bit of time before the game is released on March 6, they may want to start it up and practice using keyboard controls.
Just in case.