I just had the opportunity to review the book, 2012 Gun Laws By State, available at http://www.gunlawsbystate.com. This is the best comprehensive overview I've read. It is written in plain English, you don't need a law degree to understand it. There are a lot of excellent references to where to find additional information, which is good since the laws are changing every year. I plan to keep a copy nearby whenever I teach a class to help answer questions. I recommend this for anyone who is looking to carry or transport a firearm outside of their home.
It is available as a download .pdf version or a hard copy book. Of interest, to me at least, the soft copy is key word searchable!