Systems by Canon are very popular, especially when the budget is low. The Canon 5D Mark II (and a couple other models like the 7D) have been used for Act of Valor, Like Crazy to keep costs down, but the rig is also used when there's very little room and larger cameras won't do. Canons have also used in big budget movies like Captain America and Iron Man. Canon has introduced its first digital camera specifically designed for capturing movies, the C300.
However, new images of Rooney Mara by David Fincher puts the RED system in the spotlight today.
Here's a crop: