on a related note but with a slightly different angle on it, how about employers trawling facebook looking for shuff to discipline staff on?
there's recently been a spate of this where i work, with certain managers who obviously have little to do trawling through posts up to a year old & hauling staff over the coals using the catch-all reason of "bringing the company into disrepute"
this can be a bit of a grey area IMHO
few examples
1 employee posts something which does blatantly contravene company policy, but does so through the medium of a series of photographs, some of which include other employees. the other employees in the photos also get hauled in, despite not being aware of the OPs post
i pesron posts a status update, an ex-employee comments on this status udate berating the company. OP gets hauled in despite the post not being theirs
whilst i agree status updates along the lines of "<insert company> is a terrible company to work for <insert boss> couldn't manage his way out of a paper bag, all my colleagues are imbeciles, the guy i sit next to stinks of poo & i spent all day today doing absolutely no work..lol..roflmao!!!1111oneelvelen" are obviously out of order, there is a fine line between a company protecting its public image and cyber-stalking of employees