It turns out you can't say whatever you want on the internet. Bloggers are finding that out the hard way, as more and more of them are being sued for defamation, among other things.

Although bloggers are not given the same rights as journalists in most states, they are still subject to laws regarding libel. The perceived anonymity of the internet makes it more likely that the average joe will run afoul of laws that they might not even know exist.
Courts Becoming Busy With Blog Lawsuits | WebProNews