As far as the current competitive world seams that, Job Posting in Social Networks will not be that much helpful.
And General Networking with people can happen, and have a Chat with Good Number of Friends will happen.
For Job postings...
The people generally follow local classifieds like QUIKR, OLX and LOCAL JOB sites only.
Think this information helps you a Lot.
2nd May 2015 From India, Hyderabad