TGGP, regarding Parfit's Hitchhiker:

As near as I can tell, it's from his 1984 book "Reasons and Persons." (http://en.wikipedia.org/wiki/Reasons_and_Persons) The hitchhiker is, indeed, living in Douglas Adams' universe, where teleportation "is as nice and instinctive as a kick in the head." I believe he's using teleportation as a metaphor for the thread of personal identity between T1 and T2, and the moral obligation person at T1 has for person at T2. A quote from the wiki goes:

"Part 3 argues for a reductive account of personal identity; rather than accepting the claim that our existence is a deep, significant fact about the world, Parfit's account of personal identity is like this:

At time 1, there is a person. At a later time 2, there is a person. These people seem to be the same person. Indeed, these people share memories and personality traits. But there are no further facts in the world that make them the same person."

I'm including this here so nobody else has to spend an hour searching down broken google links. I might be a little bit off - I had to make a lot of inferences, so don't take it as gospel - and if anyone knows better, please correct my errors.

:)