As you have surely already read, we announced Adobe Flash CS4 today. I am not going to go into all of the details about what is in this release as you can find that on the website. However, I havent really used the authoring tool in some time (I barely picked up CS3), but I have really been enjoying CS4. It just feels like the Flash team nailed it this time around (Keith Peters has similar sentiments).
You can find more information on all of the new CS4 tools here.