Are you an iMovie ’08 user, adapting from iMovie HD? Do you think you’re missing those crucial transitions for your project — Fade In and Fade Out? I know I was when I first migrated to iMovie ’08. Want them back? Since iMovie ’08 does not require transitions to be tied to one or two clips, you can use transitions in pretty creative ways. This is one way I figured out how to do this creatively. If you want your “Fade In” transition back, on your very first clip, drag the new “Fade Through Black” transition. If you want your “Fade Out” transition back, you can drag the “Fade Through Black” transition after the last clip in your movie viewer.
Rob G. adds: For those who edit video a lot, this tip will seem quite basic. But if you’re an iMovie HD user making the move to iMovie ’08, it may not be obvious that you can get the fade behavior back with a “fade through” transition.
Via Mac OSX Hints