Jeremy Bernstein, Oppenheimer: Portrait of an Enigma.
I've been fascinated by Oppenheimer since I stumbled onto the mini-series about him--with Sam Waterston as Oppenheimer--one summer evening in high school.
After that, I spent some time reading about a guy who--despite being a brilliant physicist, and brighter leader--couldn't quite get it all together. He spent some time at the Institute for Advanced Study, another neat place, later in life--which is when the author met him. Most of the book, though is about Oppenheimer's life and studies before the Manhattan Project, followed by his tenure as the director there, and then the hearings which resulted in Oppenheimer losing his security clearance.
It's a well-written book, although it could stand to be better organized and planned, and Bernstein's interjections of personal anecdotes make Oppenheimer and some of the other characters come alive. One gets a feel for what it must have been like as the US became the place to do work in quantum mechanics, what the dynamics of Los Alamos were like, and who these physicists were. Rabi comes across as sagacious, Teller seems like a self-absorbed jerk, and the younger ones--Feynamn, et al.--are seen in all their youth and their promise.
Bernstein's book is worth picking up. If you're at all interested in physics, you'll enjoy this chracter sketch.