This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
I started Flex coding about a year ago and found it fairly quick to pick up the basics. ActionScript is pretty simmilar in syntax to Java. Getting use to the lifecycle methods of components takes a bit of effort, but unless you are writing your own components this is detail you can skip at the outset. There are the usual gotchas to find out on the way, but I'd expect anyone with reasonable background in another web application technology to pick it up fairly quickly.