Stéphane Corlosquet, Software engineer and Drupal developer at MIND Informatics Schema.org is a joint initiative from the major search engines to build a collection of schemas that webmasters can use to markup their HTML pages. Search engines including Bing, Google, Yahoo! and Yandex rely on this markup to improve the display of search results, making it easier for people to find the right web pages. Drupal 7 makes it easy to markup pages with schema.org, allowing to quickly build pages with structured data that can be understood by Google and displayed as Rich Snippets.
Drupal Module: http://drupal.org/project/schemaorg