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.
When Google has detected that a website is infected with malware, the new Malware details tool provides samples of the malicious code that Google has detected. The types of code that Google will provide samples of include “injected HTML tags, JavaScript, or embedded Flash files” and the tool will also identify if URLs from the website are being redirected to another website that contains malware.
Google uses the “Labs” label to identify features that are still in development and that “may break at times.”