I'll quote ricardobeat's comment above (http://news.ycombinator.com/item?id=4284877 http://news.ycombinator.com/item?id=4284877): "Not every, but 95% do. For t

I'll quote ricardobeat's comment above (http://news.ycombinator.com/item?id=4284877 http://news.ycombinator.com/item?id=4284877): "Not every, but 95% do. For the rest, there are other pssibilities and tools to make sense of it (microdata, ARIA attributes, etc). Just ignoring semantics altogether won't do any better."