Although HTML5 is not yet the standard for HTML website markups, it will become so in the very near future. Many of these new features are available in most modern browsers such as Google Chrome, FireFox, Safari, & Opera. There are already websites on the web using the new HTML5 markup (http://html5gallery.com). Moving towards to the new standard is the direction to take, whether you are creating a new website or re-vamping a current one. You don’t have to worry about older browsers, HTML5 will degrade in older browsers that do not support it and your website visitors will still be able to view your website without things breaking apart.

For more information on HTML5 you can visit some of these links below:

http://www.w3.org/TR/html5/
http://diveintohtml5.org/
http://www.apple.com/html5/