Today, of course, is the fifth anniversary of the September 11 attacks, and the iconic response by the Fire Department of New York City. To commemorate the day, MIT's "hackers" took advantage of the Great Dome ... and parked a 25-foot fire truck atop it. MIT doesn't really have a fire department, so the hackers had to invent their own shield, with the motto "Meminimus" ("We Remember"; also punning on MIT's motto "Mens et Manus"). They also provided a couple of (presumably stuffed) Dalmatians to ride along on the truck.
The "official" MIT Hack Gallery entry, including pictures: http://hacks.mit.edu/Hacks/by_year/2006/firetruck/