Marginal Revolution pointed me to New Scientist's the Next 50 Years. I'll spend some time reading it.
On the one hand, 50 years seems far too long to make sensible predictions about. On the other hand, imagine someone in 1950 predicting life in 2000. Any futurist worth their salt was predicting flying cars to Mars, but the right answer would have been 'sort of like 1950, but most people have more money and live ten years longer'. The shock for 1950 would not be computers (what? They're not sentient?), but rather gay marriage and gay adoption. Oh, oil prices would have been shocking too -- we were supposed to running on nuclear fusion by now.
So in the same vein, I'll predict that we don't get sentient AI, we don't boost human IQs substantially, and we don't prevent aging. Life in 2056 is rather like 2006, but we live 10 years longer and most people have more money. The shocking part is ....
Update 11/19/06: The authors are generally as cautious as one would expect. They are reputable sorts, and thus fearful of foolishness. There is, however, a clear trend. Several contributors speculate that we'll learn about extraterrestrial life. I suspect they mean sentience too, but that's too brash and idea. I suspect they toopuzzle over the Fermi Paradox.