Social Signals

Recently I watched a video of Matt Cutts and there he mentioned that they are now keeping an eye on social signals as well.
So should I also get some back links from social media/networking sites ?

I also would like to know how social signals affect SEO ?

 

I'm a big believer in the increasing role of social signals in search. Likes, +1s, and social links are still a noisy signal, which affects their use by search..

thanks...

 

yeah social signals also considered by google by amount of visitors getting for each profile/page

 

Social media is used for the website traffic purpose i think not for the backlink