Hidden div's -- don't do it!
It can be tempting to add all the content relevant for a rich snippet in one place on the page, mark it up, and then hide the entire block of text using CSS or other techniques. Don't do this! Mark up the content where it already exists. Except in special circumstances (for example when marking the best possible rating for review sites that don't use a 5-point rating scale), Google will not show content from hidden div's in Rich Snippets.