The Rift Mobile app is a pertinent example. I have won a single item worth about 9 platinum, about 15 itmes that are worth ~2 platinum each but that I need, and a lot of planarite. Enough planarite to make a real difference to one character. OK so I was spending my scratchgame credits almost as soon as I got them so I haven't lost out on too many when the maximum stored cap of 6 is reached, but still. That's in under a week. If I played the artifacts game, there's some on offer that go for 30 platinum or so on the Icewatch auciton houses. Naturally if the supply jumps up from the apps, the cost will go down (as the recent opening of the AH to be cross-faction has shown with plummeting prices for many things) so it will lose it's edge over time, but during that phase those with the right smart device that otherwise would have absolutely no bearing on the game are profiting.

iPhone owners have been able to do that since about christmas. Nothing on the horizon yet for Windows phone or Blackberry users, or those without a smartphone at all.