Cory Doctorow, writer/journalists who switched from Mac OS X to Linux, recommends this book, "Ubuntu Linux for Non-Geeks", saying:

It reads like one of David Pogue's excellent Missing Manual books -- a fast, crystal-clear topical tour of the amazing collective accomplishment embodied in Ubuntu. I learned something new in every chapter, and ended up with a computer that did more of what I wanted it to do, faster.

The book is available in dead-tree and PDF versions.

Although I have not read it yet so I cannot give a review, you may read a sample chapter available online at No Starch Press.

Should you buy one, please let us know here - maybe you can do a review for Hack It Linux. :)