Flash Catalyst and Flash Builder 4 have gone into public beta!

Flash Catalyst: http://labs.adobe.com/

technologies/flashcatalyst/

Flash Builder 4: http://labs.adobe.com/technologies/flashbuilder4/

There is a ton of new content on the Adobe Developer Connection about these products. Here's a few links to get started:

Flash Builder and Flex 4 SDK: http://labs.adobe.com/technologies/flashbuilder4/tutorials/

Flash Catalyst: http://labs.adobe.com/technologies/flashcatalyst/tutorials/
Flash Platform videos: http://labs.adobe.com/technologies/flash/videos/