a harry-reference in the NY Times (no, penny, it's not a bestseller list thing)

[heidi.h.tandy.c92 at alumni.upenn.edu]

No: HPFGUIDX 13235

http://www.nytimes.com/2001/03/01/technology/01NEXT.html

HARRY POTTER, the star of the children's book series, has a 
Marauder's Map, with tiny moving symbols that show the location of 
everyone in his school. It is very handy when he is out late at night 
solving mysteries and wants to avoid bumping into enemies.

Now scientists have devised a real map that has a lot in common with 
Harry's magic one. Visitors can see it at the AT&T Laboratories in 
Cambridge, England, perhaps not far from Harry's fictional home, 
somewhere in England.

There, in a three-story, 10,000-square-foot space, AT&T staff members 
have developed a constantly updated map that can track people with 
ultrasound signals as they move through the building. It pinpoints 
their locations within inches, as long as they are wearing a 
transmitter the size of a key chain.