"Starting this morning, I started to get a highlighted-box mouse-over effect along with that magnifying glass icon on most of my search result entries. Clicking on it toggles a preview image with some text highlighted as well. The image preview differs slightly depending on where the aforementioned text appears on the page."
The feature seems to be inspired by Ask.com's Binoculars, but it's a little more clever because it highlights relevant snippets, so you can quickly find them when you visit the page.
{ Thanks, Benjamin and Andrea. }