Of course, there are lots of Halo players who aren't in on the gag, crashing through the "set" and opening fire on the apparently slow-moving and non-lethal guest, host and crew, which only adds to the general awesomeness of this thing (excellent commentary on this here).
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.