There has been much debate over the years about how much influence that having a site validate to w3 standards has on Google page rankings. Matt Cutts has come out and states that it has absolutley no effect at all on P/R. Does that mean the end to all the hard work? I don’t think so.
The main reason that folks want sites to validate is that it makes it easier for sites to be cross browser compatible, which regardless of what the philistines say, is actually quite important. However, I no longer subscribe to the “must validate” at all costs philosophy. Not all validation errors are fatal to browser rendering. Take the use of the ampersand in coding. If not written as “&” then it will cause a W3 validation error. Now although this would clearly be better from a coding point of view,if not then it is no big deal.

It is true, though, that some errors will stop the bots spidering past the error even if it doesn’t prevent the site rendering and if the following piece happens to contain the all important key phrase or phhrases, then page ranking is bound to suffer as a consequence.

There are some who argue about the need for compliance to the above standards, but surely if the web is to develop then we should be ensure that there are standards that browser developers can work to and make life easier all round.

Ever ask the question, if Microsoft had not released IE6 (and IE7 for that matter) and IE8 had been closer down the line, then FireFox would not now be the second larget browser in town?