It's silly to be pushing open standards when we don't follow them for our own sites.

All Ubuntu websites should pass the W3C validation checks:
http://www.ubuntu.com/ 9 Errors
https://wiki.ubuntu.com/ 24 Errors
http://brainstorm.ubuntu.com/ 1308 Errors
https://launchpad.net/ 8 Errors
http://releases.ubuntu.com/ 15 Errors

Some of these are really simple fixes, but showing that we care about open standards is priceless.

For reference, others that fail:
Microsoft, Sun, KDE fail. Novell and Apple fail with 1 Error.

Those that pass:
Red Hat, opensuse, Debian, Fedora, Linux Mint, Gnome, Opera, Firefox and OpenOffice.org