Indeed.. Freedom of Speech is indeed a powerful thing. And the anonymity of these BBS' can only protect you so much. Slander and liable cases are very hard to prove, and damages have to be proven.
However, if one's posts are based on FACT and public records (lawsuits, and filings at a Secretary of States office, for example), there is no dispute. Facts are facts.
Here's a wonderful board on SI on that subject. Some very, very interesting reading.