Well, today I was tinkering with an iMovie project I have and I was supprised to see MPEG4 as one of the video encoding types. I installed Quicktime 6 when it was released, but I don't have the Pro version. I haven't seen this mentioned anywhere else so I thought I'd post it here.
I was certainly impressed by the quality of the exported movie vs the file size. I *think* it outputs a Quicktime encoded with MPEG4 (as opposed to a RAW MPEG4 file), so you would need Quicktime 6 to play it back, I guess.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20020827090949863