Google uses social media data in its search engine rankings. The question is WHAT TYPE OF DATA? For any corporation or small company it is ESSENTIAL that you add social media to your marketing strategy.
Why? Precisely because Google uses these social media feeds in its SERPs. Google is constantly changing the way it evaluates social media. Most social media spam is filtered out. They use Twitter & Facebook quality links in ranking = normal useful links.They also try to find the "reputation" of the author and only the social media profiles that can be crawled and that are public are taken into account. So if your promoting your business via social media, do not change your profile to "private". Trending items or "social buzz" are used as a quality signal. So if your "tweet" makes it in the Google real times results, your doing great! Getting reciprocal followers or adding lots of followers do not help much so dont go overboard and add everyone on the planet.
Social media links can help you speed up your website’s indexing and they are taken into account by search engines such as Google. In short, Google evaluates the quality of the post and the authority of the author. With Facebook, the shared links from Fan pages are treated similarly to Twitter links. No links from personal walls are used in rankings. Social media has become more important in the contribution of search engine rankings and it is crucial that you use it appropriately.