Apple Raises the App Download Limit. iPad Retina Display The Cause?

Presumably because of the iPad’s retina display causing apps to double in size, Apple raised the limit on over-the-air downloaded apps.

Higher Limit for Over-the-Air Downloads
Great apps come in all sizes. If you happen to offer a larger app, we’ve made it even easier for App Store customers to get your app wherever they are. We’ve raised the Wi-Fi download requirement from 20 MB to 50 MB so customers can download apps up to 50 MB in size over their cellular data network.