Why iPhone apps on iPad are scaled in Pixel Double mode instead of iPhone 4 Hi-Res mode? Possible Duplicate:
  Why does the iPad use nearest-neighbour scaling rather than Retina scaling for iPhone apps  




iPad runs iPhone apps too. Sometimes people want to make it bigger and they click the "2x" button. Then the OS scales the app with pixel Doubling, which makes it look ugly because the whole app is pixelated. 

Now that iPhone apps can be rendered at doubled DPI on an iPhone 4 with crystal clear quality, why doesn't Apple use this mode to display iPhone apps in 2x on an iPad? Is there a consideration other than time constraint?
It is likely to encourage developers to write native iPad apps instead of just relying on the higher resolution of retina artwork.