Guinness has taken social networking to a whole new level with their QR cup. The QR code shows itself after you've filled it with a healthy helping of delicious Guinness (don't try to be slick and fill it with ordinary beer because it wont work). Once the code appears, you can use your smart phone to scan it to do wonderful things like tweet your pint and update your Facebook status. Not too sure how I feel about publicly sharing when and where I'm slamming pints of Guinness but it's definitely a conversation starter.
(Spotted @ TheDieLine)