The creator posted a comic called Time - only one frame.
But it has been updating every half hour or so, adding a new movement each time. You can read the discussion on the XKCD forums, or view one of the forum member's snapshot of all of them together (so far).
Edited by Zahri on Mar 25 2013 21:14
Gah - I thought it was updating.. The first chance I got to look at it I refreshed a couple times without luck.. then went back a few hours later and couldn't tell if it was a different scene or not. Haven't had enough time to browse their forms in a long time.. Their "what ifs" usually come first