Gone were the days when an employee had nothing else to do other than ' work, work, work'. Consequently, there was no digression or distraction. As you rightly pointed out, social networks, media, mobile facilities have all contributed to the growth of technology, dissemination of information but like two sides to a coin, they are also becoming factors for reduced productivity, lack of concentration. Further, these digressions have also led to more inter-personal disputes, conflicts and so on.
In many organisations, where customer relation is a focussed task, employees are directed to leave the mobile phones at the Reception during working hours. Further, Firewalls have been established in the computer systems whereby employees are not permitted to access sites, which are of dubious nature or not related to business. There are separate internet kiosks where employees can go and log in to access banking and other personal accounts, during specific working hours.
It should be the responsibility of the Management to communicate to the employees, time and again, the ill effects of such digressions and the resultant reduced productivity, lack of concentration, security threats, accident possibilitites etc. In all organisations, there will be regular intake of trainees and employees and they have to be inculcated these factors right from induction / orientation stage.