sorry if it was posted before.
In synchronous mode the master camera using the cameras menu allows multiple slave cameras (or slave flashes) to be link together. Once the master camera triggers, all the slave cameras simultaneously releases. Thus, a motif can be take from different angles at the exact same moment.
In continuous mode, the slave cameras will shoot after the master camera. Canon gives the example of a camera that shoots three frames per second (fps). In a paired arrangement, the frame rate doubled to 6 fps. With three cameras linked to the frame rate increased to 9 fps.
this patent would make a setup like this very easy: http://www.youtube.com/watch?v=_AuyVz89AXg&feature=player_embedded