So, not everybody's camera will be able to be set up for this, but it is something that people with the 7D, 5DmkII, and any other camera with a more fully featured video mode should keep in mind.
Yes, its kind of a longer read, but I REALLY recommend it. There's a reason people want to keep making movies with film, and its because of the look of film. Digital is starting to emulate it more, but you won't even get close if you don't follow the 180 degree rule.
In general, if you're shooting video at 30fps, you want to be using 1/60th shutter speed. At 24fps, you want 1/48th. Basically doubling your FPS gives the correct shutter speed to shoot at to get 180 degree shutter. Full explanations on why, etc. found at the link!