For years there have been services which let you receive all your flight data via your cell phone, but none have been approved as boarding passes. Now Lufthansa, which experimented with in flight WiFi with Boeing, is making the paper go away on two routes in Germany.
This is great for those of us who are connected. It means you can be SMS'd your flight details, run the screen past the bar code reader and get on your flight.
That said, don't expect it to happen anytime soon here in the USA.