The W3C CSS Working group has posted the last call working draft of
Selectors Level 3.
"Selectors are patterns that match against elements in a
tree, and as such form one of several technologies that can be used
to select nodes in an XML document. Selectors have been optimized for
use with HTML and XML, and are designed to be usable in
Style Sheets) is a language for describing the rendering of HTML and XML documents on
screen, on paper, in speech, etc. CSS uses Selectors for binding
style properties to elements in the document.
This document describes the selectors that already exist in CSS1 and CSS2, and
further introduces new selectors for CSS3 and other languages that may need them."
New pseudo-classes include
:empty. There's also
a negation pseudo-class and a general sibling combinator.