In the meantime, a late-night observation on the Anthropic Principle. For now, I'm not going to worry too much about the strong vs. weak versions, which are a non-sequiteur to my point.
I've mentioned before that I'm naturally attracted to the Anthropic Principle -- I find many-worlds interpretations of existence to make intuitive sense, and to help explain a lot of philosophical quandries. The Turtle-Free musings are pretty deeply grounded in it. But when you look at the Principle too closely, it does lead down some strange roads.
For example, it's interesting that everyone seems to speak of the Principle in the abstract, as being about "us". Paraphrased, it says that, "We observe a universe that happens to be able to support us because only such a universe would allow us to exist to make the observation". The funny thing is, the same observation holds true if you substitute "I" for "we".
The reason this gets weird is that it would seem to imply (if you take the fairly extreme view of many-worlds that I've been following) that personal immortality is almost a necessity. Consider the times you've had a brush with accident, and reflected on that, saying, "I could have been killed". In the extreme many-worlds multiverse, you were -- those times, and a nearly-infinite number of others. But if you'd been killed, you wouldn't be around to make the observation, so you always observe the near miss.
Now carry that logic through. If every mathematically possible state of this universe is in some sense real, then there is always some state in which you make it past the gauntlet, again and again and again. Accident, disease, even age are surely somehow conquered, albeit through increasingly-unlikely sets of apparent coincidence. Eventually, you must find yourself down a blind alley of somehow managing to survive endlessly despite utterly preposterous odds, simply by dint of there being a state of the universe where you can make that observation.
Of course, this begs all kinds of hard questions -- not least, it starts showing how difficult questions of identity are in many-worlds interpetations of the universe. For every version of you that inexplicably survives to age 200, there might be a million million that don't, pruned off from the ability to make observations, and there is no obvious way in which all of those parallel identities are meaningfully linked. Indeed, it puts the entire concept of continuity of consciousness on pretty shaky ground when you delve into it: "I" get to be immortal only if I adopt a rather fluid definition of "I".
Still, it is intriguing -- a bit hopeful, a bit frightening -- to consider the notion of personal immortality by accident, coincidence and the fact that you can only observe a world that you are in: no matter where you are, there is some happenstance that gets you by. So long as there exists a universe that can support me making these strange observations, I get to keep making them there...