Having eventually found time to play around with the new-look iMovie, I was infuriated by the apparent difficulty in importing movies and seeing already-created iMovie projects -- I kept getting an error code -120 whenever I attempted to import movies. Following the problem through, I discovered that iMovie will not follow aliases to an external Movies folder; I have an alias in my home directory which points to a FireWire disk.
After several minutes declaring the new software "useless junk," it occurred to me to replace the alias with a UNIX soft link (ln -s). Hey presto! All my movies appear in the Project section, and I can now import clips at will. And the best bit? As far as the Finder is concerned, there's no difference at all.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20080204152429462