How is a Turing Test defined?
Although Alan Turing is of course a very important computer scientist, the Turing test is only superficially related to computer science. It is more related to philosophy.

As long as machines exist people have wondered whether it is possible to construct a machine that can think. But to answer this question we must first answer the question what it means -- what is thinking? Turing tried to circumvent this philosophical problem by changing the question a bit: the goal is no longer a thinking machine but a machine which is indistinguishable from a thinking being.

The Turing test was intended as a thought experiment to make the reader think about (artificial) intellingence in some way, but it appealed to a lot of people. So people started to organize Turing tests for real, and if you're doing real Turing tests, then of course you need real rules. Last year the Turing test organized by the University of Reading attracted a lot of attention because, according to the rules fixed for that particular Turing test, one computer program beat the judges. See here for the press release.