Adobe TV has posted a video where I talk about some of the new effects capabilities in the next release of Flex, codenamed 'Gumbo'.
For example, the effects can now animate arbitrary objects and types (not just UIComponents and Numbers), which enables things like the new FxAnimateColor effect. Also, there is a new 'easing function' interface that makes the built-in easing functions more flexible and also 'easier' for custom implementations. And there's new repetition behavior that makes reversing and looping animations simple.
Work is still ongoing: we're adding more functionality to the effects system constantly. In fact, I'd better get back to that now. Meanwhile, check out the video for a preview of where we're headed: