Last week, Google unveiled its new weapon in social marketing, the +1 button, which is quite similar to the Facebook like button. But it has one major distinction, +1s will become a search ranking factor in Google SERPs.

Google will start to look at +1′s as one of the many signals we use to determine a page’s relevance and ranking, including social signals from other services. For +1′s, as with any new ranking signal, we’ll be starting carefully and learning how those signals affect search quality over time.

Content recommended by friends and acquaintances is often more relevant than content from strangers. For example, a movie review from an expert is useful, but a movie review from a friend who shares your tastes can be even better. Because of this, +1’s from friends and contacts can be a useful signal to Google when determining the relevance of your page to a user’s query.
Google will be releasing the new +1 button slowly, starting with english USA results on Google.com. But as a heads up, Google will soon release an experimental search site that uses the +1 rankings. If you want to know when buttons are available for your site, you can sign up to get notified at https://services.google.com/fb/forms/plusonesignup/