iMovie '08 Library Compressor
iMovie '08 certainly has sparked debate in Mac circles. Is it a step forward or a step back? Only time, and personal preference, will tell. There is one thing that no one can debate: saving disk space (I am sure someone can argue that since disk is so cheap, why bother but they are the vocal minority). This AppleScript application from iNik converts all those DV clips in your iMovie library into beautiful, efficient H.264 clips (giving you the choice of several different compression levels) which translates to lots of freed up space on your hard drive (your mileage may vary).
The application is free but you need to have Quicktime Pro and Apple's Developer Tool installed on your Mac to make it work.