To improve site's user experience, many webmasters discovered the advantages of using Ajax and creating dynamic pages that act as web applications.

Ajax site's one of main issues is Googlebot which has great understanding with HTML structure links. HTML links will have difficulties in finding its way around sites particularly to browser uses JavaScript for navigation. We are working to get better understanding about JavaScript, for the meantime your best bet in creating your site is to make sure that it is crawlable by google and by other search engines to provide HTML links to your content.