The Wired blog ‘Epicenter’ reports on a study commissioned by the IT staffing company Robert Half, which found that 54% of US companies have banned the use of social networking sites such as Twitter, Facebook, MySpace and LinkedIn sites at work. Apparently, the primary concern is loss of worker productivity, but fears over unknown legal and brand exposure may also play a role in this.

“Using social networking sites may divert employees’ attention away from more pressing priorities, so it’s understandable that some companies limit access,” said Dave Willmer, executive director of Robert Half Technology, in a statement.

Another study conducted by Nucleus Research also indicated that employees who use social networking sites at work do so up to 2 hours a day. 87% of employees admitted they weren’t using the sites for business, but for personal purposes instead.

Does your company have a social networking use policy in place? Perhaps a good time to check before HR comes knocking.

Update: I just found this short presentation on slideshare…