Ayaan Hirsi Ali, a critic of Islam who helped make the film about women in Islam called Submission with Theo Van Gogh who was murdered because of it; and Flemming Rose, who published the pictures in Denmark. (The picture on the right, Michael Leunig, is a different story and it is very unclear why he is being targeted - he penned a cartoon comparing Israel to Nazi Germany which was not published in Australia and someone else submitted it to Iran's Holocaust cartoon contest under his name.)
Look carefully at the pictures: they have what appear to be gunshot wounds drawn in to the foreheads of Hirsi and Rose:
So, in the United States, today, Muslims apparently threatened to assassinate people who disagree with them.
And if you are unclear as to what these people ultimately want, just have a look-see at this lovely sign: