Divya Manian runs through many of the latest stuff coming in CSS. Including several things I'm hearing about for the first time, like specifying unicode range for an @font-face and canvas-as-background.
If you can't get enough, this talk by Tab Atkins (only works in Chrome) covers even more upcoming stuff, including more I'd never heard of. Things like
image-interpolation (determines how images scale, like keeping sharp pixel boundaries), setting font-size with
ex which is based on x-height (will be awesome for icon fonts), and an
attr() function which allows you to use attribute values in styles.