Here is one: http://ofps.oreilly.com/titles/9781449398583/ and this is how the book will look like once it's out: http://www.readwriteweb.com/hack/2011/03/nodejs-book.php Since node.js is still under development, you'll find very few text on it. Still try to look for code/examples on official site and videos are available too if you do a google search.

the node API is not yet stable so a node.js book would date to quickly. pure js books are a better bet. I love Javascript patterns by Stoyan Stefanov. There are two other good Javascript books.