Yes, you read that properly. The W3C has released the first specs for CSS4. Now that most modern browsers are well on their way to supporting CSS3, the W3C is getting started on the next “layer” of CSS.
The Selectors Level 4 document already has one feature that is unfortunately missing from CSS3: parent selectors. You will finally be able to do things like selecting all a elements that have an img element inside them, with this syntax: $a > img { ... }. The draft also mentions “nth-column” selectors, for styling all of the cells in a specific table column.
Of course, it’s probably going to be awhile until we start seeing browsers supporting this on a usable level.
Before anyone comments about the CSS3 spec not being “finished,” note that W3C specs are not prescriptive. They’re not “finished” until they’re pretty much supported by the major browsers, and changes have been made based on the implementation. A couple of the documents for CSS3, Selectors Level 3 and CSS Color Module Level 3, are already under the Completed Work section of their website.
