Adobe just release free source Action Srcipts 3.0 API: Libraries at Adobe-Labs.
The APIs:Libraries contains:

  • corelib. Several basic utilities for MD5 hashing, JSON serialization, advanced string and date parsing, etc.
  • FlexUnit. A unit testing framework for Flex and ActionScript 3.0 applications based on JUnit.
  • Flickr - A wrapper for the entire Flickr API.
  • Mappr - A wrapper for the entire Mappr API.
  • XML Syndication - Libraries for easily parsing all versions of RSS and Atom.
  • Odeo - A wrapper for the entire Odeo API.
  • YouTube - A wrapper for the entire YouTube API

This source is very helpfull for people who started working using Flex Builder Beta