I heard part of Bob Edwards Weekend yesterday. The discussion was about developments and improvements to the electric guitar that made it possible to define new genres of music (rock and roll, bakersfield country, etc) They discuss the instruments played by the legends (Les Paul, Chet Atkins, Jimmy Page, George Harrison, etc.) Manufacturers discussed: Fender, Gibson, and Gretsch.
Update (2011-08-24): I guess the only option was to listen to this live. For whatever reason, the podcast has gone away.