On April 11 I put an entry in this blog about EFF's "How to Blog Safely (About Work or Anything Else)"
They've published another good guide:
EFF: Legal Guide for Bloggers
Like all journalists and publishers, bloggers sometimes publish
information that other people don't want published. You might, for
example, publish something that someone considers defamatory, republish
an AP news story that's under copyright, or write a lengthy piece
detailing the alleged crimes of a candidate for public office.