You can check in and choose their seat (window or aisle) between 30 hours and 30 minutes before the latest check-in time. When checked in, you can request confirmation via SMS. Then, when you arrive at the airport, you print off a boarding pass at a kiosk and drop off your baggage. The only thing you need tech-wise is net access on your mobile phone.
Good idea – and should save both time and stress – unless you lose your phone.
Via The Register