In the past, employees might have had a reasonable expectation that their employers were not allowed to monitor surfing practices. Not so anymore. Internet surfing has become so ubiquitous, and the potential liability and loss of productivity so large, courts are siding with employers in cases where they have fired employees for surfing activities.
While it would obviously be best to include the companies surfing monitoring practices in the employees signed employment agreement, courts are becoming more lenient in what notice and warnings are required. As employer monitoring in now pretty much a given in the workplace, courts find that a computer use policy, distributed to the employees constitutes sufficient notice.
With the law in this area changing so quickly, it is important to update your computer use policy regularly. If your in-house lawyer or corporate lawyer is not up to date on the latest changes, ask them for help locating an attorney specializing in this area to review your current policy to determine if it is in line with your current practices.