JSON CSS
An interesting proof of concept from arc90 that implements some simple programmatic concepts like variables, inheritance, syntactical cascading, and browser detection within CSS. The implementation uses JQuery, and they have made it available over at Google Code.
There’s a lot to like here. I’m seeing a slight flash of unstyled content while the scripts load first time up, which won’t be ideal on slower connections, but once the files are cached it seems to play very nicely.