Erica Klarreich does a nice job of introducing the notion of pseudorandomness in a general setting. She starts by describes the basic problem of generating truly random bits. She then moves on to practical approaches that people have used to generate randomness, and also talks of what it means for a sequence to be random (loosely of course). She also describes the more interesting notion of cryptographic randomness, with a brief quote from David Wagner.
The article also discusses simple algorithms for generating randomness, the linear congruential generator being one that she alludes to. She also covers the von Neumann trick for converting a biased coin into a fair coin.
All in all, a decent article. I complain constantly about science writers, so it seems only fair to mention when one does a reasonable job. She could have gone a little deeper into why we care about randomness at all, and I would have liked to see some comments from other experts on pseudorandomness in the academic community, but overall, the article was nice.
A little surfing pointed me to her home page, which has a collection of other articles she has written (mostly on mathematical/computer science-related topics). She also has a Ph.D in mathematics ! She's one of us !!
Via Marginal Revolution, which is also an entertaining note on the game theory of Rock, Paper, Scissors.