What's up with the beheadings?

I continue to hear talking heads on the tube suggest that the purpose of the beheadings is to intimidate the West. Its certainly possible that the terrorists might hope for a collapse of western resolve as happened in Spain. But I think they are aware that for the most part, these acts will stiffen resolve. Rather, like Belmont Club, I think that these beheadings are aimed at a different audience: the Islamic world. This makes these attacks more insidious.