The Out of Bounds Church by Steve Taylor, says Pernell Goodyear, is the best book on the emerging church to date. He has just blogged his way through the book which means, if you were too stingy to buy it, you might be able to partake of its fruit. Chapter One is a free read.
I would say it is in the top 5 of the 50+ books that sit on my emerging church shelf. (more like 70 now)