I've seen this news from Apple talking about new iOS app submissions needing to be built for retina devices:
https://developer.apple.com/news/?id=3212013b
I know that it says that apps and app updates "must be built for iOS devices with Retina display", which is pretty generic and could maybe include the iPad, but the text only mentions the iPhone 5, and the linked page for "iOS Human Interface Guidelines" only talks about how to make your app ready for the iPhone 5. No mention of retina iPad whatsoever.
So, will it really be mandatory for submitted iPad apps to be compatible with the New iPad resolution of 2048x1536 starting from May 1st, 2013?
Yes, as of 1 May all new apps and app updates must support retina and non-retina devices. If your app is an iPad or Universal app then it must support both resolutions of the iPad. If your app is an iPhone or Universal app then it must support 3.5" and 4" screens as well as non-retina and retina versions.
来源：https://stackoverflow.com/questions/16180745/does-apple-now-require-all-ipad-apps-to-be-retina-screen-ready