Joseph Chez at TPM Cafe makes a point that I have heard elsewhere in the last week:

What is needed is for the United Nations to issue a strong declaration, warning the Iranian government, including clerics, that they will be held personally responsible for the safety of the civilian population and for the opposition leader.

For the record, the UN High Commissioner for Human Rights Navi Pillay said basically this on Friday. "The legal basis of the arrests that have been taking place, especially those of human rights defenders and political activists, is not clear," she said. "It is the responsibility of the government to ensure that militia members and regular law enforcement agencies do not resort to illegal acts of violence."  This is probably as tough a statement as can be expected from the United Nations secretariat or its agencies. There is a line between standing up for human rights -- which is the right and proper roll of the UN -- and meddling in the electoral politics of a member state. I think Pillay's statement dances that line quite artfully.