It's "subtlemob" to you.

Another review I did for the Londonist:

http://londonist.com/2009/11/review_subtlemob.php

No photos on this one.. Not allowed (takes away from the subtlety of the mob, you see). Plus it pouring rain, and I was preoccupied with waltzing in the middle of the road with my neighbor. Love you, public art.