Schema.org is a new collaboration by Google, Microsoft, and Yahoo! to start standardizing website code. They are trying to help you code your website in a better way so that they can understand your site better and its contents.
But did you know that by using code on their site you may be infringing upon a search engine patent? They specifically state, in the terms service, that even though they are granting you a license to use that code, you may be infringing on their patents. I really don’t have a problem with that, but you should be aware of this.