As part of the iPhone 4 introduction during WWDC 2010, Steve Jobs announced iMovie for iPhone, with one-click sharing. This is basically iMovie from the iLife suite for Mac brought to the iPhone. Up to 720p editing and most of the functionality you'd expect, including transitions and Ken Burns effects.

Make beautiful HD movies anywhere with iMovie, the fun, feature-rich video editing app that’s designed for iPhone 4. Create a video postcard of your day at the beach and publish it to the web without leaving your spot on the sand. Or make a movie of your child’s birthday party and send it to your parents while the party is in full swing. You can start several projects on your iPhone 4 and finish them whenever you want and wherever you are.

It will be in the App Store for $4.99