There's a PBS show tonight (Wed., Jan 5) called Do You Speak American? which is a 3-hour program about linguistic differences across the US, by Robert MacNeil.
The PBS web site is chock full of good stuff, including transcripts of all three hours, at http://www.pbs.org/speak/transcripts/. There's also an educator's site about the program, which might be interesting to some of you: http://www.pbs.org/speak/education/. I will buy the companion book for Hampshire's collection.