whats the big deal? To me it just seems like there making html work with js to produce ajax? Is that all it really is? Or is html trying to do without js to make its own ajax?
HTML5 is still in development . It simplifies a lot of things but it still needs more tweaking and features . Unfortunately just like CSS3 a lot of browsers have problems digesting it .
The only browser that has any such problems is IE. All other browsers handle the stable elements and properties just fine.
Javascript has as much to do with HTML5 as HTML4.01 but there are more APIs available and the ability to draw in the window using canvas. Audio and video is natively included along with a number of semantic elements. Google for "What's new in HTML5".
You can do a tutorial at w3schools.com too for HTML 5 which should give you a better understanding of it.
You can expect more semantic approach to the markup. for example: we've div, which is used as blocks for section, articles, container. in the upgraded version you may have tags like "header", "footer", "article", "section" etc. Other respected DPers already pointed few more features/ up-gradation are expected.