A survey by ScanSafe says that Facebook, Twitter and other Web 2.0 and social networking sites have been banned in about 76% of workplaces over fears about the impact of social networking on business.
(The problem will be as the next generation, who've grown up with Facebook et al, join the workforce and then start exhibiting signs of withdrawal when they can't get their Twitfix. So, if you face this dilemma, it might be time to become your own boss.)