Flex 2 beta 3 was just publicly released at http://labs.adobe.com. There are some nice changes in beta 3. I won't list them all here, but a few changes that I've been most impressed with so far are a bunch of nice enhancements to the Flex Builder IDE interface and 
performance and much better java-to-actionscript serialization. The flex framework source code is now distributed with the SDK and builder, which I think is very cool.I've been spending a lot of time playing with various members of the Flex 2 product suite and so far I've been very impressed. So far I cn say with confidence that Beta 3 doesn't disappoint.