I've found this book to be quite solid so far: <a href="http://shop.oreilly.com/product/0636920032175.do" rel="nofollow">http://shop.oreilly.com/product/0636920032175.do</a><p>I'm about a quarter to half of the way through and it's been interesting and quite thorough even though it's still a "beta" book. The content is a little high level so some familiarity with distributed systems principles is useful but the text is very approachable and easy to understand (so far).<p>I got it after seeing several recommendations in other HN threads so I'm not the only person that has found it useful.
I'd love to read an actual review of the book, but this was thin to the point of being blogspam. The article's author told me nothing about the book, except that it apparently contains 80 design patterns about distributed systems that the reviewer promptly forgot.
Some constructive criticism on the font used for headings: it's atrocious. If that's your handwriting, good for you - it's pretty good handwriting - but it definitely affects the readability of the content.