Emacs nXML mode with built in validator

For the last two years there has been a major mode for Emacs that I just found. There has long been an XML mode which didn't interest me. This is nXML, or the new XML mode. What caught my attention is on-the-fly xhtml validation! Wow! Make a mistake and the word 'invalid' appears on the location bar and the incorrect markup is underlined in red. How about direct insertion of unicode entities? There's the usual syntax hi-liting and tag insertion/completion.

Here's O'Reilly's XML Hacks chapter about nXML mode.

It's available as a Debian .deb package, RPM and a .tar.gz.

cheers,

gary