If you're familiar with the interactive thumbs up and thumbs down icons on Facebook, the ad team has announced the addition of "Like" to Facebook Ads. By clicking on the "Like" link, users are able to express themselves and share this expression with their friends. When a user likes an ad, their friends will be able to see that action in their version of the ad.
Another progressive step being taken by Facebook to provide businesses with targeted advertising and a greater ROI on their advertising investment.