Macbidouille reports that the 5.02 update to iMovie HD changed iMovie HD's minimum resolution requirement from 1024x768 to 1024x720. This is very interesting, because even the low end iBook has a screen resolution of 1024x768 already, and it's basically impossible these days to buy a desktop monitor less than 1024x768.
However, many people have been looking at utilizing the Mac mini for HTPC purposes, and many high-end TV sets support the 720p resolution, which is 1280x720. Apple's change in the iMovie's requirements seems to be a nod to this group. Now Mac minis can be used to edit iMovie HD projects on 720p HDTVs directly.