If any of the Living Computers folks are paying attention to this thread: you guys should set up an exhibit on phone phreaking. Blue boxes (and other boxen) should be easy to build, and it'd probably be easy to obtain historical boxes too. You could dial into Project MF [0] or set up your own vulnerable phone network to tinker with.
Check out the Communications Museum sometime - no phreaking exhibit per se, but much more in that direction. It's closely to Living Computers, in Georgetown. http://museumofcommunications.org
[0] http://projectmf.org/