Don't get me wrong there are some epic features in there, all the new form elements, geolocation and sockets to mention a few.. but these all come at a price and will probably not find themselves in the vast majority of sites. I think apps are most likely to reap the benefits from the new standard.
And herein lies the rub. Geolocation and WebSockets APIs are not HTML5. They are independent APIs developed by W3C with nonstandard support across browsers and have introduced serious security issues. The same goes for WebGL, Storage API, Web Workers, and a whole host of other APIs/features that people associate with HTML5, yet are not HTML5, are not (and might never be) cross browser supported, and might be scrapped or changed at any time due to the severe security issues that continue to creep up. In addition, there is no consensus on a minimum video codec support, so the video tag remains nonstandardized and does not enjoy cross browser support.
Worst of all, is that the link above lumps all of these HTML5 APIs into one lesson on "HTML5" and uses names like "HTML5 Storage" (even though he admits it is a seperate API later) that further obfuscate what HTML5 actually is and the mess that is surrounding the current sea of independent web APIs and lack of consensus on codec support. It is a great site for getting an overview on new web technologies, but it really perpetuates the mythical HTML5 creature and spurs people on to make posts in threads like these where they attack people for not seeing the grand vision that HTML5 offers. And when you try and point out the wizened man behind the curtain, you are labeled a troll who is ignorant of the splendor of HTML5. Both Antheus and VildNinja have provided correct answers in this thread. Antheus is right to point out the flaws and shortcomings of HTML5, and VildNinja appropriately linked what the OP wanted to see, even if most of the stuff is not HTML5.