It's 2:00 pm on a cloudy November afternoon, and nearly one hundred developers are furiously typing on laptops at the Microsoft complex in Cambridge, Massachusetts. A large table is covered with energy drinks, coffee, and half-eaten pasta, the evidence of a massive, all-night coding session. One of the developers is blowing a straw over a circuit board, trying to play "Mary Had a Little Lamb" on a makeshift electric harmonica. Another group is holed up in a conference room in front of a massive LED grid, which pulses in time to a techno beat.