Prentice Hall has made the leap into open source publishing, in no small measure due to the impetus provided by Bruce Perens, author, programmer, researcher, and father of the open source movement.
He states on this site, “I’ve convinced Prentice Hall PTR to publish a series of books that have their text under Open Source licenses.” Not surprisingly, it is called the Bruce Perens’ Open Source Series, and will include 6 technical books that will be freely distributed on the web, and will not go out of print, under the terms of the Open Publication License.