It includes a video by Ely Greenfield, an engineer from the Flex team, talking about the new way to skin components using MXML which I think is really worth checking out.
What I’m really interested to see in Flex 4 Builder is how the interface will be to aid designers to customise all these components. Will it look like the current CSS panel? Integrated with it? Whatever it is I just know things are only going to get more exciting! 😀
Download the Flex 4 SDK and start playing with things! *w00t~!*