Most people are used to a product cycle that goes like this: Release a new version every year or two, each more capable than the last. Ensure that it’s backward-compatible with your existing documents.
iMovie ’08, on the other hand, has been totally misnamed. It’s not iMovie at all. In fact, it’s nothing like its predecessor and contains none of the same code or design. It’s designed for an utterly different task, and a lot of people are screaming bloody murder.