Mike Nott

Google, who for some reason choose NOT to bother making their site and SERPS fully standards compliant, finally have a results serlvet that does validate – http://www.google.com/xhtml

From the DocType it can be seen that this is intended for mobile platforms:

[code lang="html"]

[/code]

Also selecting Mobile Web (Beta) shows some interesting results. Could be time to starting thinking about Mobile SEO.