Momentum: Hacker with iPhone take over NY Times Square screens

I posted this to try and find the original story, unaware that it had been deleted.

http://news.ycombinator.com/item?id=2322401

I've been trying to get my head around how this actually works, but have so far failed. I hope it's not fake. Anyone have any insight?

EDIT: Consensus seems to be it's a fake, shame!