In the google serps there is now a new feature called Google Instant Preview. When you mouse over the search results, a popup preview of the site appears on the right hand side. This is a feature that has been used for years by visual search engines, and more recently by Bing, but this is the first tim that Google have taken a stab at it.

The video below demonstrates how it works:

Personally I don't really like it, I find it a bit obtrusive but I can see that it would appeal to many people, especially those that have not encountered the technology before.