I gather these sensors are called "map" sensors, but with the GPS work Arduino people are doing, plus the "map" function built into the language, I was afraid people looking for the automotive "map" SENSOR might miss the good discussion of these interesting devices, to be found at...
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1263536081
... because it refered to them, correctly, but perhaps ambigously, by the term "map".
(If you have comments on ManAbPress sensors, may I suggest you add them to the above, or start a new topic?)