Can Online Personality Assessments Revolutionize Hiring?

Here’s a thorny issue: Should companies use applicant’s Facebook ‘Likes’ and develop a personality profile based on these preferences?  It may be less expensive and time consuming than administering psychometric tests, which are usually reserved for high level executive positions. Do you think watching online behavior is a fair way to assess someone’s personality?  This could make for a lively lunchroom conversation.