Author’s note: Peter Gasston and I kindly remind readers that the CSS3 spec is far from finished, so note that I mean all of the current (as of June 2008) CSS3 selectors.

It looks like David Baron is working hard on new CSS support for Firefox 3. His latest blog post tells us that he has finished up support for a bunch of CSS3 selectors, available now in the Firefox nightly build:

We now support :nth-child(), :nth-last-child(), :nth-of-type(), and :nth-last-of-type() (see bug report) and :first-of-type, :last-of-type, and :only-of-type (see bug report)

This will be released with the next major version of ‘fox (probably 3.1). It looks like support for Media Queries is next. Hurrah! Good work David!