Oh, you wanted to increment a counter? Good luck with that!
With distributed and disconnected systems, counting isn't as easy as 1-2-3. Russell gives us a brief run down of why, and what you can do about it. Starting off with the innocent thought of "how hard can this be?", he eventually settles on the fact that there is no "perfect" answer, but an understanding of the trade offs and an informed choice is the best we can do.