What does prayer achieve?

(From Guardian Unlimited)

When I consider my Christian academic friends -- people who are smarter, better read and harder working than I am -- it's clear that Christianity is a very dangerous profession. Three have daughters who died in their 20s; another has a daughter who is a drug addict. Parents and spouses get Alzheimer's disease when they don't get cancer. I imagine they all prayed for these things not to happen. I know they all still pray.

So what is going on here? What is the point of all that prayer? This is hardly a new question. It has been around at least since Job. Nor is there any hope of finding an answer that will convince everyone. But it is …