Apple announced that binaries with sizes of up to 4GB are now accepted in iTunes Connect. This means that you can now download an app as big as the total size of the launch iPhone 2G.
Also we can think that a new Retina screen is coming up, although I’m pretty sure it’s probably to accommodate developers and the iMac with Retina 5K display. Perhaps a pro app developer that has reached the 2GB limit previously in place.
Of course Apple also said it does not affect the 100MB limit on 3G/LTE app download size.