Google is today testing a major new layout to their search results – full page previews of the target site and blue backgrounds behind the search results when you hover over them. Source- http://www.blogstorm.co.uk/google-starts-showing-full-page-previews-in-search-results/
I think that every time when Google tweaks their algorithm or technology, rather than being a threat to the SEO community it is actually an opportunity to more work. Bing also has a similar feature with "More On This Page". thanks.
its really great move by google if it implement, visitor had good chance to see design and overview rather click on it.