MotionBuilder is widely used, for example in mainstream products like Assassin's Creed, Killzone 2, and Avatar.
It is notable for being one of only five pieces of animation software (the other four being Muvizu, Moviestorm, Xtranormal and Autodesk MotionBuilder) that use a real-time "WYSIWYG" view to let animators see the results of their work immediately, and to play back animations in the viewport.