Haven't mentioned any books for awhile, so will just briefly cite 3 that have been around for a little while now, though I've only read the last one:
"The Theory That Would Not Die: How Bayes' Rule Cracked the Enigma Code, Hunted Down Russian Submarines, and Emerged Triumphant from Two Centuries of Controversy," The Lancet:
A book I received a review copy of but never got around to reading, is "Magical Mathematics" by Persi Diaconis and Ron Graham, recounting the mathematics that underlies a lot of magic tricks. Even though it didn't engage me, I won't argue with success, as it has received almost unanimous thumbs-ups in reviews I've seen, including this one from CTK Insights:
(...As a sidenote, speaking of magic, a book I did love, but on neuroscience not mathematics is now out in paperback: "Sleights of Mind" by Macknick and Martinez-Conde.)Finally, the one review volume I have had a chance to peruse, is this year's issue of "The Best Writing On Mathematics 2011," edited once again by Mircea Pitici. I almost feel I could duplicate the short review I gave of last year's initial edition for the current volume. It is again a fine compendium of great variety. If anything, I would say it has a bit more philosophical reading and other material that a layperson can readily follow (while still also including several quite technical entries). And again, whatever your own proclivities in math it will contain some contributions of interest and others probably not-so-much, but all-in-all a very worthwhile volume. I look forward to this series continuing well into the future.