Apple has released iMovie ’11 9.0.8 with a typically cryptic note about the update: “Addresses an issue related to third-party QuickTime components that could prevent iMovie from opening.” However, according to this support page, it appears that one of the third-party culprits is the 3ivx component (used to enhance compatibility with such camcorders as the Flip Ultra and Flip Mino). If you currently have 3ivx installed, version 9.0.8 of iMovie displays a warning dialog that explains how to remove the component. ($14.99 new from the Mac App Store, free update through Software Update or the Mac App Store, 1.08 GB)
Option-Click in Scroll Bars for Jump Scrolling
In Mac OS X in general, and thus in most native Mac OS X applications, hold down the Option key and click anywhere in a window's scroll bar to jump to that spot (rather than scrolling one screen). If you like this behavior, you can make it the default in the Appearance preference pane. For "Click in the scroll bar to:" select "Jump to here."