Google.com HTML & XHTML are Invalid
Most of us think W3C Validation of our web pages is important, especially in reference to correcting problems with Google. In fact most of the websites which are giving SEO Tips are asking us again and again to keep our website/blog code validated!
After checking http://www.google.com in W3C Validation i found that Google himself has invalid HTML , XHTML.
The simple question i wana ask here ” Why would Google want our web pages to be validated? If the Google himself has got 40 Errors, 2 warning(s). ( LOL )
Validation Does Not Matter to Google :
“My typical answer is, normal people write code with errors. … there is no way that a search engine can remove 40% of its content from the index, just because somebody didn’t validate or something like that. … we don’t have a signal like that in our algorithms and its probably for a good reason. … But validation and sort of closing off those last little things usually doesn’t matter that much to search engines.” — Matt Cutts ( Google Software Engineer )
Its all up to you people weather you like to have a W3C Validation for your website/blog or not. Next time you don’t wana bring Google in this! 
You are most probably wrong. HTML5 is still under very huge preparation and its NOT standard yet. Google is using it and some BETA codes just for the sake of new functionality and new user interaction.
All Google is asking us, is to close the tags properly and that doesn’t mean our document has to be foolproof.