Is western society really becoming secularised?

You hear a lot about the "secularisation" of western society nowadays: about how the church (or mosque, or temple, etc.) no longer plays as central a role as it used to, and about the rise in atheism and agnosticism.

My question is - is this really happening? What statistics are there to support this allegation? If it is happening, does it vary from country-to-country and ethnicity-to-ethnicity?

You only have to browse through questions in many different sections here in Y:A, and in other fora elsewhere on the net to see a lot, even a disporoportionate amount of issues regarding religious issues: evolution vs creationism is an obvious example, but so is debate of the Archbishop of Canterbury's statements, and the allegations of rising Islamic fundamentalism.

Are these debates truly reflective of the opinions and moods of modern society, or is it just a side-effect of the openness of the internet for such issues to be aired?