Paperback: 112 pages
Publisher: Dark Horse Comics,U.S. (30 Jun 2007)
ISBN-10: 1593077734
ISBN-13: 978-1593077730
Category(ies): Webcomic compilation
Another compilation, this time covering 2003. Since Penny Arcade is still going, that means we can expect at least another 4 volumes.
This has a handful of pages of sketches from Gabe's archives, but is otherwise pretty much the strips with commentary.
(Edited to correct typo in title)
Volume 4.