One thing to keep in mind as furious right-wingers embrace the latest distraction from Iraq, the cancelled Mozart opera in Germany. The controversial heads-of-the-gods scene, Mohammad's head included, does not appear in the original Mozart version --
The production of Idomeneo by Hans Neuenfels was only mildly controversial when it was first performed in 2003. The plot of the opera, first performed in 1781, centres on Idomeneo, the King of Crete, who is saved by Poseidon from dying in a storm. To repay the god of the sea, the King is obliged to sacrifice the first person that he sees on reaching safety. This turns out to be his son.
The opera, with the usual entanglements of love and jealousy, shows how the King tries to escape from his debt to Poseidon. In the end his sacrifice entails handing power to his son and the woman he loves. The epilogue, as conceived by Neuenfels, has the King coming onstage with a bag of cut-off heads. With great care he props them on chairs. The message is clear: the gods are dead and humans have to take over their own destiny.
UPDATE: Brad DeLong notes the addition, among other criticisms of a Peter Beinart article.