Jewish synagogues, Catholic churches, Nativity scenes and all sorts of other religious symbols get defaced all the time. But anything Muslim gets "defaced" (comparing spray-painted Nazi symbols on Jewish synagogues or broken statues of the Virgin Mary to slapping some bacon on a wall), and the media goes hog wild...uh, no pun intended.
I'm not defending the actions of whoever did it. Just saying that this happens to other religions as well. Some of it, as mentioned in other posts, is done as "art." And some of it is done as "intellectual discussion." Either way, if you bash Christians, it's freedom of expression. If you do anything that remotely offends Muslims, then you're an intolerant bastard.
Sorry, the double standard is dumb, silly and stupid.