Here I am sticking Dan while he tries to score a flag capture.  Halo 3 rocks.  This is a screenshot of real gameplay.

[I ended up uploading to Flickr while I figure out how to link to the screenshot on bungie's servers]

[UPDATE] Some people have complained about my "real gameplay" statement.  Let me clarify.  After the game, I replayed the film of the game, during which I paused at this frame, detached the camera, took this picture (which automatically makes it available from bungie.net).  I am the guy at the top of the ramp.  I've just thrown a grenade toward Dan, which subsequently stuck to him and killed him.  So, no this is not what I saw during the game, but if someone else was in the game with there head where my camera was, you would have seen this.  My point was that it is not a "cutscene", manually posed render or other pre-rendered sequence (although you could argue the pre-rendered point since screenshots are slightly higher resolution than is being processed in-game).