@Mike:
While I agree that validity is not needed to make a page render (after all, we have to keep IE6 compatibility in...), creating valid XHTML that IS compatible AND valid is not a problem. The problems start when people are used to HTML 4 and using the depreciated tags and attributes.
Just because the Web is a pile of crap does not mean that every new page needs to be a pile of crap as well. Most Validation errors on SO are so trivial, it shouldn't take too long to fix, like missing quotes on attributes.
But it may still be kind of pointless, given the fact that the W3C does not have any idea where they want to be going anyway (see HTML 5) and a certain big Browser company that also makes operating systems does not care as well, so a site could as well send out it's doctype as HTML 1337 Sucks and browsers will still try to render it.
