Once in a while there is a new version of HTML that comes out and brings innovations to the way we create and optimize websites, and the way websites are perceived by search robots.
Nowadays we are up to HTML5, which brings with itself quite a few revolutionary, useful and simplifying innovations.
First and foremost the new standard allows for code of WebPages to be more compact.
This will not only affect quality of the sites but also improves loading times for the pages and general readability of them so now more sites can without any problems be loaded on mobile devices which will eliminate the need for .mobi standard I think. Yay! equality of rights and one standard for all devices!
HTML5 Love
Secondly this new incarnation of markup language will have clear sectioning of the code parts. Page segmentation is more precise and transparent and is much more easily readable. If before we have used <div> tag for just about anything now there are such things as <header>, <sidebar>, <article>, and <footer>. And those will play important role in optimization of pages, since it is obvious that article part of it carries the most important weight. It will be much easier indexed by robots and will eliminate confusion and indexing of unnecessary information. Footer and header in turn will carry supplementary information.
Links will also be given quite a distinction in the new version of HTML. If in previous ones you only had one now you are going to have multiple variations: alternate (for the address on the same page), author (information about author), external (yep good old reference to outside page), help (well… needs no explanation), license ( where the legal stuff goes), prev and next ( if the pages connected to each other in logical order), and hey nofollow ( just as before to let robots know not to go there).
Finally there are attributes video and audio that will allow imbedding of those formats since hardly any site can do without media today and letting robots know they are there, and elimination of many plug-ins such as Flash, which now be handled directly by HTML5 and spare user from hassle of installing all kids of extra stuff.
Taking in account all of the above I’d say HTML5 is a future star and although it is still being modified it is a good idea to start using it now to keep up with technical evolution.