Morgen Kaufmann has recently published a book on open source:

Innovation Happens Elsewhere : Open Source as Business Strategy

I was one of the external reviewers for the book, and it's a solid effort. Over the years I've talked to lots of people about open source and answered a lot of questions. Many of those questions are addressed in the book. There are chapters that cover the reasons why you might get involved in open source, and there are several practical chapters that discuss the nuts and bolts of setting and participating in open source projects.

The authors, Dick Gabriel and Ron Goldman, are old time Lisp hackers -- I've followed Gabriel's work for years, so it was a treat to be a reviewer. Both have been involved in open source software since before it was called open source, and they've had a lot of experience working with some of Sun's open source communities

If you have questions about open source, or want to read a good treatment, you should pick up this book (the content will be online at some point). I know that I am going to be directing people to the book when they want to know more about open source.