In mid May, Adobe Labs released the beta version of Flash Player 10 (code name 'Astro' and a nightly build of Flex 3 SDK that can compile content for Player 10. The new version of the Player has caused great excitement in the Flash community and for a good reason: Player 10 is loaded with new features, including native 3D support. Player 10 uses ActionScript 3 just like Player 9, but it supports new AS3 classes and methods. In this tutorial, we use the most basic of the new AS3 3D methods. These most basic methods allow for creating great 3D effects with just a few lines of code.

You will find instructions how to download and install Player 10 as well as Flex 3 SDK nightly build at the Adobe Labs: http://labs.adobe.com/technologies/flashplayer10/.
You will find there also the updated AS3 documentation that contains all the new classes.

We recommend a great video tutorial by Lee Brimelow at gotoandlearn.com:
Flash Player 10 Beta: Getting Started.
This tutorial show you step-by-step how to get started.

You will find a list of new AS3 classes that Player 10 supports on Manfred Weber's Weblog:
Key New Features.
Without this guide it is hard to sift the new features out of the documentation.

We also recommend an excellent tutorial by senocular at senocular.com on the new ActionScript 3 drawing API:
Flash Player 10: New Drawing API Features Explained

A word of caution: Installing the beta version of Player 10 requires uninstalling any earlier version of the Player from all your browsers. You may not want to do it on your main development machine. Authoring Flash Player 10 content at this time (June 1, 2008) can only be done through the nightly build of the command-line Flex 3 SDK compiler. We are all eagerly awaiting Flash CS4 beta to have a more handy authoring environment.