Offering an app like Angry Birds for free doesn’t mean that the game can't make a bunch of money. Rovio supports the free game on Android with advertising and does well at it according to estimates. Rovio is also looking at new ways to make money on the game.
Rovio has teamed up with a carrier in Finland called Elisa to sell upgrades to Angry Birds users starting next year called Eagle upgrades. The new system will allow the carrier to grab in-app charges for Rovio since the Android market can't do that directly.
The service will let the Angry Birds player call in an eagle airstrike to kill off those pigs if they just can’t figure out how to get past a certain level. Each airstrike will cost the player real money and would presumably charge the fee to the users mobile bill.
Via The Register