Fired! For blogging?? Not really.
<soapbox>
I wish people would stop using the headline "Fired for Blogging". It's simply inaccurate and plain WRONG. These folks were fired for using a mass-medium (i.e. the Internet) in a very non-anonymous personal way to, at least in the views of their employer, breach the the confidentiality agreements of their employment.
</soapbox>
Could these agreements (which are essentially default contracts enforced by state and federal legislation) have been worded more precisely and explicitly by their employers? Absolutely.
Could these companies have taken a more 'enlightened' view of the situation and merely requested that the 'infringing information' be removed from public view? Absolutely.
But the facts of the matter are that all of these folks were 'at-will' employees and that's part of the risk/reward trade-off one makes (at least in the United States) when entering into an 'at-will' arrangement. Once something is publicly disclosed, you can't undisclose it. The only other available remedy under the law would be a tort (i.e monetary compensation).