Be careful who you add as a friend, or what groups or pages you join. The more friends you have or groups/pages you join, the more people who have access to your information. Companies are looking for ways to prevent company confidential and proprietary information from slipping through the firewall. Most incidents probably occur via email or file transfers but IM chat tools, blog posts, Twitter messages and even online resume content could disclose proprietary company information. Even using social networking sites on company time or using company resources could be a violation of the companys acceptable use policy. Before you become the corporate poster child for some publically humiliating episode from using social networks at work, check your corporate AUP to make sure you arent violating the policy.