1. Brand New Interface
2. New and Improved Flash Video Importer
3. Improved Skinning of Components
4. Exporting Motions and Animations
5. Import Photoshop Files

Read More about the New Features of Flash CS3 at ZDNet

Related posts:

1. Photoshop CS3 & Photoshop CS3 Extended
2. Using the ActionScript 3.0 Debugger
3. Using the MouseWheel to Scroll in AS3
4. Why Flash?
5. Using any JavaScript in Flash and Flex