From the website of the mega-famous author of The Tipping Point and Blink:
In Blink, I probably owe a bigger intellectual debt to Tim Wilson (and his longtime collaborator, Jonathan Schooler) than anyone else, and Strangers to Ourselves is probably the most influential book I've ever read. It also inspired two, separate New Yorker articles of mine: "Getting Over It" and "Personality Plus." In fact, I once gave a talk at the University of Virginia--where Wilson teaches. He was sitting in the front row, and I had the distinctly uncomfortable feeling, half way through, that I was simply giving the audience a kind of popularized version of Wilson's own work. Imagine giving a talk on physics, in 1910, and saying "you know, there's this thing called relativity," and then spotting Einstein in the front row. In any case, "Strangers to Ourselves," is a beautifully written book. In it, Wilson asks the question: what, at the end of the day, can we really know about ourselves? His answer: not much. Or, at least, not nearly as much as we think we can know. But it's a tribute to Wilson, that in giving that answer he is never disheartening or depressing.
The book Gladwell raves on about is Timothy J. Wilson's Strangers to Ourselves: Discovering the Adaptive Unconscious, which was published back in 2002 by none other than Harvard University Press. More on the book, including table of contents and an excerpt, at the main HUP site.