A lot of companies have social media clauses in these days - mine certainly does.
Even if I'm posting in a personal capacity, should those posts/tweets bring the company into disrepute I would be called up for a disciplinary hearing.
Depending on what I had posted, it could be considered as gross misconduct and thus a sackable offence.
It's pretty reasonable imho. If you are a senior manager of a company who has a responsibility to uphold equal rights and set an overall standard of good, professional conduct, tweeting or posting on FB accusing GOSH of murder, or saying the lawyer needs to be hit with a hammer is not exactly an indication of good judgement or belief in process and the rule of law.
How then can an employer trust you to uphold such legislation in the workplace?
I think people get totally swept up in this stuff in terms of their visible social media profiles and forget that many years down the line it could have profound implications (or in some cases more immediate ones) wrt employment.
I note that there's a lot of very young people posting on the CA page......