A clever bit of advertising gimmickry from Guinness: these pint glasses bear QR codes than can't be read when the glass is empty, nor when it is filled with amber-colored beers. But when filled with black, murky Guinness, the revealed QR code can finally be scanned: "it tweets about your pint, updates your facebook status, checks you in via 4 square, downloads coupons and promotions, invites your friends to join, and even launches exclusive Guiness content."
Yeah, so the last part is a bit of a nightmare.
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.