http://www.google.com/webmasters/tools/richsnippet... is where you test the rich snippets tool.
In simple words, it serves the purpose of displaying additional data when search engines display results. Which means it would only 'beautify' your search engine listing, thus increasing CTR to your page.
A wide variety of formats are available using rich snippets. For example:
1) Author pictures can be displayed on SE results.
2) "You > can > have > a" breadcrumb display of categories on your website.
3) Rating Stars may also be displayed using this method beside any listing.
Hope that helps.