I've had similar (Score 3, Informative)

Working for a well-known retailer in the UK part-time while at University, one person I know lost their job because of (or at least partly because of, there *were* other factors) comments about the company and some people working for it on a social networking site. Shortly afterwards, the guidelines on computing were revised, and everyone asked to sign them, including a section on not posting negatively about the company or its employees "for example social networking sites or web-logs (blogs)"