Apple has informed developers app sizes submitted to the App Store are increasing from 2GB to 4GB (however, the 100MB cellular download limit remains):
The size limit of an app package submitted through iTunes Connect has increased from 2 GB to 4 GB, so you can include more media in your submission and provide a more complete, rich user experience upon installation. Please keep in mind that this change does not affect the cellular network delivery size limit of 100 MB.
What does this mean? It means apps can now be larger in size, allowing developers to add higher quality photos and videos, which most likely will benefit game developers (or a larger 12.9-inch iPad??). It also means the available storage on your 16GB iPhone or iPad (or 8GB iPhone) will shrink further if you are downloading large games.
Apple also announced today Testflight groups, to allow developers to group testers into groups to provide specific instructions and for A/B testing.