Few months back, Google released rich snippets in the search results. That meant Webmasters could mark up their HTML with richer data using micro formats and RDFa in order to display the richer snippets in their search results.
It has been observed that until Google actually displayed the richer snippet in the Google results, a webmaster had no idea as to how the Google snippets would look like. As matter of fact, Webmasters wanted a solution to preview the snippet and validate the coded the page correctly.
According to Brian Ussery, Google released a beta version of the Rich Snippets Testing Tool that allows you to plug in any URL, not just URLs that you own via the verification process in Google Webmaster Tools. With this tool you can preview the snippet data. For example,your LinkedIn profile is available for preview without your owning LinkedIn.