A key component of HTML 5 is that it adds new elements that help better define what is on the web page. This allows for the segmentation of the page to be easily distinguished. Once HTML 5 becomes more widely adopted by the large web browsing companies, search engines will be able to use the new elements to help index relevant information.
Currently we use <div> elements to organize our web pages. These have no descriptions nor do they add any semantic value. The new HTML 5 elements will be identifiable and help search engines organize which data is the most important on your site.
This element can give search eninges a bit of an idea on where the navigation, company name, and logo will reside.
Your content is the most important part of your site. the <article> tag is probably the most valuable element in HTML 5. This element allows you to define the main content within your page.
Normally a footer will include auxiliary information such as copyright, licensing terms, links to static pages, and social media widgets. This section could see an uptick in value as HTML 5 evolves.
As it stands today, many of the web browsers have adopted HTML 5 and support it. However, there are known issues with Internet Explorer 9 rendering HTML 5 elements correctly. Look for the new release of IE this summer to fix this and be fully HTML 5 compliant.