"With more and more companies and recruiters using social media to find and screen potential employees, it's fast becoming a vital part of the job search process." Source: Power Up Your Job Search
Be careful about the impression you make online. Employers may google you to screen your application. According to a survey of employers in the United States:
Not having a social media presence may be a disadvantage. You may be competing for jobs with people who use social media to advance their career.
"It can be just as harmful to be absent from social media sites as it is to be present on them in an inappropriate manner: a candidate who projects a particulary positive image online may seem more interesting to an employer than one who does not have a profile." Source: Social Media and Job Searching Among Young Canadian Workers