After the tip about stopping the Ken Burns plugins in iMovie3, I thought I should let people know a more direct approach. If you click on iMovie.app and select File -> Get Info, in the dialog box you should see a tab marked Plugins.
Click the triangle to open this section. Simply uncheck the plugins you don't like. You can also use this tip with iPhoto, iTunes, and probably a load of others I haven't checked yet.
What could be more logical?
[Editor's note: In looking through the list, I didn't see the Ken Burns effect specifically listed, so I'm not sure you could disable it in this manner, but this is still an interesting feature. I'd known about the Languages section of Get Info, but not about the Plug-Ins section.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20030210060845166