You'd be surprised at just how many people are still using table based layouts, inline styles and JavaScript, they keyword meta tag, and a ton of techniques that were cutting edge in 1997! And I'm talking about professional design firms!

I love HTML5 and I see no reason not to use it today. I know that there are still people using browsers that won't support the majority of features but we can still at least use the new tags and doctype with the JS shiv. For everything else there are well known ways to serve up new hotness to modern browsers and old lameness to old browsers. For example we can use the video tag with the last line before the closing tag being an embed for a YouTube or other video player as a fallback for older browsers.

I think there are 2 and a half reasons why HTML5 isn't being widely adopted yet. First, newbies are being fed old techniques from online tutorials and old books. Secondly, many of the cooler new features of html5 require JavaScript to work (Local Storage and Canvas for example). A lot of people still haven't gotten on the JavaScript bandwagon (including me, I admit. I can use jQuery plugins and get how they work but god help me if I had to write a single line of JS from scratch!). And then reason 2.5 is that people are just set in their ways. There are a ton of people who had been fed the rhetoric about semantics, divitis, and how to "properly" write HTML while learning XHTML and waiting for the I,agin any XHTML2 spec to arrive. Some of those people are set in their ways or have sour grapes about XHTML not being the new hotness after all the hype.

I have a question though. Why is it that in the HTML5 Boilerplate the doctype tag is in all lowercase? My text editor highlights it like its wrong. I usually capitalize the word DOCTYPE and leave html in all Lowe case. Does it make a difference?