3. It builds work relationships.

Companies spend a fortune on lame team-building exercises and outings, which build work bonds only because everybody is suffering from the same forced interactions.

Social networking, on the other hand, can allow employees to build bonds at no cost to employers. Yes, people interact with family and friends who are not part of the company, but usually people interact with co-workers, too, and this can help build teamwork.

4. It converts real-time interactions into asynchronous ones.

A social interaction controlled by others (also known as an interruption) can devastate attention. I've found that a five-minute office "pop-in" by a co-worker can set me back the equivalent of an hour. This kind of concentration-shattering interaction is allowed -- and even encouraged -- in the workplace, while social networking interactions are frowned upon or even blocked. Why? Social networking interactions on Facebook and Twitter are, by definition, controlled by the user. They happen between, rather than in the middle of, bursts of focused concentration. They restore productive concentration without interfering with it.