I cannot believe so many threads here and elsewhere treat this issue as some kind of dilemma.
Employees are paid to work.
If your business uses facebook to network / gain business then it should be accessed - if it is irrelevant to the business in which they work then why the hell should they expect access?
If you paid a taxi driver to take you home would you be happy for him to pull up and text his mates for an hour?
Would you be happy to queue out the door of your bank because all the tellers were caught up in a 'who's best, Ninja's or Pirates?' forum discussion??
Come on people - no wonder why so many businesses are struggling, they are too busy wringing their hands and worrying about the poor little lambs not being able to 'like' their friends comments and see the latest pic of them falling over drunk.
Simple fact is, you are there to do a job.
You are trained up and paid to do a job.
If you struggle, you will get assistance and extra training.
If you are unproductive because the job has such little value to you that you would prefer to play farmville then get out and let us get a proper employee in the door who will make the most of their opportunity to work and get on.
Next we'll have some smart arse taking their employer to court claiming facebook access is a human right.