Charlie: "Bluntly, Joe's blog provided an excuse to sack him", I agree with this. From the quoted comments in the Guardian article, it looks to me like a boss with a grudge, and the skipping of at least two disciplinary steps is out of order, whether or not Waterstones have a case for any action (which they might). I think that Joe has a case for unfair dismissal on those grounds (IANAL; see how we are all being more careful of what we say online already?).
"... write something outside of work without their explicit permission and your employers may use it against you if they want to fire you."
Here's where it gets interesting, in two ways. The first is that some companies, especially US ones, have always taken an industrial-feudal outlook on the actions of their employees. The cliche of a '50s company man was that he at all times fit the company image, and so did his wife and kids. In return for this loyalty, he and his family would be taken care of from cradle to grave. In recent years, the attitude seems to have become that the company demands total loyalty from the employee but feels no obligation in return, as in the cases where employees have been fired for making moves to find a new job. I myself have been shaft^w downsized in the past, and the hypocrisy of the company, in particular the HR staff, stung severely. Maybe a response in the future will be for workers to form support groups to help themselves, not just as trade unions, but in a form such as labour companies. A return to guilds would serve corporations right.
The other thing is - how public a forum is a blog? the defamation laws are very wide-ranging, and
this article holds that they act to limit free speech. Even an overheard conversation in the pub might be cause for action (slander in this case). Newspapers have to be careful about libel, as do authors, but the letter columns of newspapers are held to be the opinions of the writers, not the editors, so maybe weblogs should have the same automatic status? Or comments online should have some other kind of relevance limitation, so that less regard may be paid to them in law. Maybe there should also be another form of defamation; "malicious (mis)quoting", a sub-category of libel, to protect bloggers and usenetters from having their opinions used against them.
As it stands, Big Brother Google makes just about everything online into a public forum with a historical record so that ill-considered, wrathful or even just drunken words years afterwards can come back and haunt you. How do we respond to that, then? Maybe changes in manners so that one doesn't make a statement unless one really means it? Doesn't work on Usenet, I know that. Doesn't Speakers' Corner have some kind of customary protection?