Anyone listening to NPR this week? They have a 5 part series on the science of spirituality (sounds like an oxeymoron to me). I caught two of the shows, but haven't formed an opinion yet.
In a nutshell, scientists have discovered that neurons firing off in a particular part of the brain account for the "spiritual" visions some folks have. Some folks believe that this is proof that peoples visions are all in their head, so to speak, while more religious folks beleive that we are all hard-wired for the supernatural - this is how god intended for us to be able to communicate with him.
check it out if you are interested