Download: i5m_iMovie2FCE v0.9
It's an Applescript droplet that you can drag the iMovie DV stream media files onto and it'll run away and convert them. There's also a standalone version of the script if you want to run it from the script menu on individual files, etc. It's a 0.9 release since for ease of development in Applescript it doesn't include any error handling, etc. Also I've just realised it assumes 16 bit audio. Although I think you really should be working with this anyway. I'll sort this for a later version.
Related to this post on how to manually convert iMovie captured media from the DV Stream format to a FCE compatible one and this thread, "Importing Files Captured in iMovie HD" on Apple Discussions I've figured out how to automate the process with Applescript. I thought it would be a lot harder than it turned out to be, hence why I've only just got around to it. Next I'll have to figure out how to turn it into an Automator action. That would be cool and an excuse to look at Xcode.