New stage rendering core in Flash 10 * Live video playing in author time (meaning you don't have to compile your movie to see how your video will be displayed) * New timeline, similar to After Effects (or Director as some people have pointed this out) * No more keyframes * Transfer objects between Tweens. * Bones * Runtime Inverse Kinematics * And more....

Disclaimer: Not all features listed in demos actually make it to the final release