Quote from SDfreelance: SEO Secrets Revealed
Progressive links and progressive content is the name given to content that is not displayed until the mouse click or hover on a certain part of the page. Researchers have determined that many of the sites who lost traffic after google’s panda update …
… HTML5 provides AJAX as a standard and AJAX allows for additional progressive content to be downloaded – using AJAX for progressive content provides the best experience for the user.
The researchers post at webmasterworld Can a Mega Drop Down Menu create problems? also it should be noted that to much or to many progressive elements may not be the best user experience … “One moment of truth came for me when I tracked which menu links were actually being used by site visitors. That analysis showed me that all those hover menu options were NOT being used by visitors. Only a small subset mattered, and there were other ways to help people find those pages.” … the only reason to use progressive content is to enhance user experience – keyword stuffing will clearly be seen by the search engine robots.
Using AJAX is the ideal method to provide progressive eye candy. Pages load faster because these hover elements are loaded after the page loads, these elements can be loaded before the hover event or streamed and load seconds before they are displayed with the buffer time being the animation of the view port opening.
jQuery being employed to make this development faster and compatible with older (pre HTML5) browsers.