pageoneresults - 12:56 pm on Feb 9, 2011 (gmt 0)
My thoughts on this...
When most people place the validation link on their page they use the old school URI of validator.w3.org/check?uri=referer -- but that page does not exist on W3C, it's just a throw away reference and it can only be accessed by referral directly from your site.
^ Absolutely the best way to validate pages on the fly.
If instead you use the new school way of understanding that it's all about conformance then you will use validator.w3.org/unicorn/ such as validator.w3.org/unicorn/check?ucn_uri=www.example.com%2F&ucn_task=conformance (me luvs unicorns).
Nice try but I don't believe it is doing what you think it is. Those references are disallowed via the W3 robots.txt file. That means Google will find them, from that new school way of understanding, and show a URI only listing when performing certain searches.
If these are new sites and you are performing searches and finding those URI only references, that means Google knows about the documents but that is about all.
If anything, I'd go out on a limb and say that your throwing just a little bit of equity at a black hole. ;)
By the way, the /check? produces the same results so they are both displaying the same behavior, it is not a throw away reference as you say.