Microdata is one of the rich snippet formats that is supported by the major search engines (learn more on schema.org) and is natively supported in HTML5 in a really powerful and simple way. These formats can help robots parse the data on your pages more accurately and in greater detail. Google uses a few of these formats to tailor result displays in certain situations. There isn’t a ton of support yet, but anything that improves semantics is usually a good idea, so I’ve started adopting this into my web design habits.
You can check how Google is parsing your rich snippets to make sure they’re crafted correctly using the Google Structured Data Testing Tool by pasting your url into the box, nothing to download. I will be creating example pages since I believe that’s one of the best ways to learn how to use the different schemas.