In the US, Kentucky lawmaker filed a bill to make anonymous posting illegal. The website operator who would fail to enforce the law (i.e. let somebody posting without identifying him/herself) would pay a fine.
there are two problems here: first, free speech; anonymity is a key feature of free speech. See previously anonymous mail which can be bad or good. Secondly, criminal policy: is it the best way to fight bullying to require loss of anonymity? (10 March 2008) http://www.techdirt.com/articles/20080310/110506493.shtml
Compared with the following, it is interesting to see that readers of websites sued the website owner/operator, along similar lines as proposed by the bill above. But they did not succeed (action dropped) and are even now a target of a lawsuit for libel, for the website owner losts his job because of the damage the first legal action brought. Which raises incidentally the question of the presumption of innocence! (10 March 2008) "When Law Students Get Angry... Lawsuits Get Filed" http://www.techdirt.com/articles/20080310/014651487.shtml
And where the above idea becomes interesting is when are at stake websites ranking or rating individuals for their performance in their job. Libel is obviously a danger; but this is only part of the iceberg: harassment and personal vengeance could be coupled with anonymity and give extremely hurtful results for the people targeted. Contrary to the author of the following post, I do not think accountability can be achieved via websites of this sort. There is no control on facts, no procedure to promote fairness; whatever an individual has done, s/he cannot be deprived of fairness of procedure. Otherwise, we become like those monsters we are supposedly fighting. (10 March 2008) "Police Accountability Is A Good Thing" http://www.techdirt.com/articles/20080305/075621447.shtml
The French courts clearly took the opposite view from the author of the above article. They ordered a website ranking teachers nominally to stop publishing the teachers' names, thus taking away the whole interest of the website. The co-founder of the website Stephane Cola is obviously unhappy and considers there is a breach of freedom of speech, making a parallel with ranking institutions, but I think the issues are muddled here. It's OK to rank institutions who have no career as such and have a duty of accountability to all; but to rank an individual whose career and privacy is directly at stake with no chance to put things right reaches an other level.
Sorry the article is in French "La justice dit non aux noms des professeurs sur Note2be" (3 March 2008) http://www.01net.com/editorial/372605/la-justice-dit-non-aux-noms-des-professeurs-sur-note2be/