Case rejected against those children who created a fake profile of their headmaster; lucky because in some countries like France defamation is a criminal matter not usually a civil law issue like in the US and UK (well criminal law does get involved but rarely).
Principal Loses Lawsuit Against Students and Parents Over Fake MySpace Page--Draker v. Schreiber (Eric Goldman - 22 august 2008)
Draker v. Schreiber, 2008 WL 3457023
But it does not mean disciplinary action cannot be taken. See "Judge Says School Can Suspend Student For Fake MySpace Page Of Principal" (19 September 2008)
A change of standard in the law? Sorry have not read yet the case, so can't comment much "UK High Court Recognizes That Defamation Standard Should Be Lowered For Online Forums" (11 August 2008) Judgment is available on the BBC website in PDF format