While I haven't actually heard the original story (I have the gist), it's certainly not the first time that someone has lost their job due to comments they have made via social networking media. There was a case last year I think with someone making negative comments about their employer on Facebook who consequently was sacked.
The thing about social media is that someone is always following/reading, and you need to take that into account. I think journalists & other 'media personalities', and others under the public eye need to be extra vigilant, because lets face it: if I got on twitter & made a comment that someone found offensive then they might complain or just not read my feed anymore, no harm done. Someone under the public eye can be seen (even if it is not the case) as stating opinions as a representative of that organisation or whatever, people have an organisation to complain to, so it can get out of control for something that someone might have just said off the bat.
(That was very long and rambly and I hope it makes some kind of sense.)