The big search engines (Google, Bing, Yahoo) have published a common schema for improving how search engines index pages. This is done by adding in “microdata” attributes to your HTML so the search index gets better (some?) context of what it's processing.

Could be big stuff for some sites!

http://googleblog.blogspot.com/2011/06/introducing-schemaorg-search-engines.html

 http://schema.org/