In in Blogger Help Forum: Something Is Broken, we see a fair number of complaints asking why Blogger won't remove a blog that contains trash talk (aka "libel" / "slander"), which is targeting them, personally.
Impersonation may involve identity theft, and is a TOS violation. Blogger / Google will resolve impersonation issues, by removing a blog or website that contains impersonation, when properly reported. Defamation, however, is not so simple.
What one person sees as libel or slander, another person (maybe in a different country, and bound by a different set of customs and laws) may see as free speech. Libel and slander are civil or criminal issues, which must be decided by the courts system. Other legal conflict will involve various governmental agencies - differing from country to country.
The Internet, in it's ability to casually bring together people from different geographical, legal, and political systems, is going to cause international conflict, from time to time. As each new Internet feature, such as the recently released Google+, debuts, we're going to see new forms of personality clashes. It will be interesting to see how all of the conflict shakes down.