Initially Social Media used to be considered as having fun among connected friends and families. There was less involvement about business and brand promotion in it. With time Social Media has evolved a lot and now people are getting paid for it even social network sites are getting paid for business promotions too.
While recruiting in any firm, Social Media plays a vital role in understanding the candidate socially and professionally a little bit. Here is a nice infographic showing LinkedIn involvement and roles on job market and how the skills on Social Media help people in getting various roles.