That's not a a rumor, it's a fact. How do I know? Because iMovie 11 has a Rolling Shutter Removal option, and these kind of things tend to move back and fourth between the two programs.
And anyway, I didn't want to headline another post about iMovie; it's starting to turn into the iMovie blog...
I had intended to try some experiments with it, but Jeff Carlson at Macworld beat me to it with a little sample clip in his review. The function is part of the image stabilization function; when you turn on either the Stabilization or Rolling Shutter functions, iMovie puts up an "Analyzing for Stabilization" progress bar and spends a few seconds or minutes processing the clip. This processing pass isn't repeated if you turn Stabilization on after you turn on the Rolling Shutter reduction. Parameters are: Low Medium, High and Extra High, which means you have to pick and test to see which works for your footage.
Macworld: iMovie '11