However, there's a catch. Employees that spend excessive time surfing Facebook for non-work purposes still need to be managed and informed that the behavior is not acceptable.
On companies that don't allow access to sites like Facebook, the study had this to say:
Banning Facebook and the like goes against the grain of how people want to interact. Often people are friends with colleagues through these networks and it is how some develop their relationships.
As someone who uses both Facebook and Linkedin, I can see the benefit of being able to see a snapshot of a colleague's life or get an idea of their background if we haven't met before. However, I've also seen people spend too much time on social networking sites, so I'm not sure the benefits would outweigh the risks in all circumstances.