Missed 2 negatives:
1 - Referrals: locating and retaining talent is good and, quite often, employee referrals are a great way to do that. However, if your employee is spending an excessive amount of time on SM and recommends others who do likewise, is this good? Do you really want more employees who spend their workday on FB/twitter, not working?
2 - Performance: if you hire professionals and they act like school kids then you deserve the reputation of being a company that doesn't produce and lacks innovation.
Yes, most have all the SM on their mobile phones, but setting professional standards of use and employee expectations sets a company apart as having an idea of what quality is vs. what's a day care center.
