When you mouse over a search result, Google shows a bigger Instant Preview icon in a vertical bar. Mouse over the bar, and you'll a large screenshot of the page, the links to the cached paged and other similar pages and the Google +1 button.
Like the previous variation of the experiment, Google's header and the search options sidebar are sticky, so you'll see them even if you scroll down. It's the perfect interface for implementing infinite scrolling, which is also tested in a separate experiment.
{ Thanks, Herin. }