Google is rolling out +1 within their organic search and paid search results. +1 is a way to like, recommend, favorite, or share content directly in the search results. Instead of having to click into a site and “like” each individual page, you can now quickly “like” search results so your friends, family and connections can find the content you recommend.
According to the Google blog, the +1 is an additional relevancy factor and will affect the search results displayed. Users must have a Google account and a profile to be able to use the feature. Google also offers a +1 video to explain the theory behind +1.
Google has been trying to harness the power of social networking for some time now, and this appears to be a way they can introduce it into search without the need for a separate social network platform.