Now that we've started to get more in depth on the abilities and uses of Lightroom 3 here on the blog, I thought it would be worth repeating "Ken's 2 Thumbs Up" endorsement of Scott Kelby's "Lightroom 3 Book for Digital Photographers".
I'm not going to launch into any "point-by-point" review. If you want that just click the link above and read what other Amazon purchasers have to say. I will say, however, that I LOVE this application and every time I pick up this book I learn something new. In fact, it's thanks to this book (and it's predecessor on Lightroom 2) that I've been able to become proficient with the tool. While it can be technical, Scott's book also points out just how intuitive it is which makes it that much easier to understand and use. If you're using Lightroom, you need this book in your library.