Windows users can now download a preview release of Flash 9 on Adobe Labs that is basically the same as Flash 8, but allows Flash Developers/Designers to output their content to Flash Player 9.
There is however one new awesome feature included in there for you to play with, the Document Class feature, which makes it easy to assign an actionscript class to the main timeline (the main timeline then becomes an instance of the specified class) instead of using the old hack which was basically to have something like the following on the first frame of the main timeline:
import com.flashguru.someProject.SomeClass; this.__proto__=SomeClass.prototype; SomeClass['apply']( this , null );