Should we forget the HMTL new elements ( nav , header...)

Google likes them. Google can easily see what part of the site is what. I don't see how they're confusing? An article is a big block of text, a section would be a slider...the rest is self explanatory.

The section element represents a generic document or application section…The section element is not a generic container element. When an element is needed only for styling purposes or as a convenience for scripting, authors are encouraged to use the div element instead.

The article element represents a component of a page that consists of a self-contained composition in a document, page, application, or site and that is intended to be independently distributable or reusable, e.g. in syndication. This could be a forum post, a magazine or newspaper article, a blog entry, a user-submitted comment, an interactive widget or gadget, or any other independent item of content.

isn't that confusing? :)

I've read that google read's your site better . But i think its better to use schema.org for your sitemap

I can recommend reading the HTML5 book from www.abookapart.com. They have a total different view on semantic markup.

The use of semantics like section or aside are a little confusing, still. It might be a good idea if Treehouse would give a little insight on that subject.

Yeah you should ignore them as the spec and reality don't currently match up. If anyone hasn't read that book and is confused on what's wrong with the HTML5 structuring they can take a look at the 3 part series blog article series on the The harsh truth about HTML5?s structural semantics .

If you know about all the issues with the spec but you still want to use those elements anyway, either because you are working on an existing project or your company/client requests it you can check out this great primer on learning to use HTML5 semantic elements