Google has added two tools to their Webmaster Tools service under the “Labs” label.
The Fetch as Googlebot tool shows the contents of the page and HTTP response headers that Google receives for a specified page. Being able to see exactly what Google sees, when it requests a page, can be helpful in diagnosing problems that can cause Google to have trouble crawling and indexing websites. It can also help in diagnosing hacks that modify the content of pages when Google requests them.
Google uses the “Labs” label to identify features that are still in development and that “may break at times.”