We've adopted Cairngorm as our preferred framework for Flex development. Now we are up and running with it we are finding it clear and simple to use and that is starting to show real dividends in terms of speed, flexibility and reliability.
But we did find it quite hard to find a good starting point for getting up and running. Essentially we had to setup a few of the Cairngorm example apps (available from cairngormdocs), open all the files and flick backwards and forwards between them until it started to make sense. The good news for newbies is that a few brave souls have started posting getting started articles. The best of these so far is from David Tucker. I'll add links to the various parts as he adds them :