Apple have come out with version 4.8 of iTunes and it now plays videos (and here) that can be bought as part of music albums. Almost certainly a baby step leading to an Apple Movie Store at some point in the future.
Also in the video area, if you’ve upgraded to Quicktime 7 you can now enjoy high resolution versions of some trailers and they look awesome, they skipped a bit on my system but the sharpness is insane.