According to Dan Rayburn, EVP of StreamingMedia.com, Apple has built a Content Delivery Network system (CDN) for specifically for downloading iOS, O SX and different content that Apple releases.
This system will allow software launches such as Yosemite and iOS8 (coming out this fall) to be downloaded at a faster rate and won’t have as many issues with downloading failures as in the past. (Hundreds of complaints on Apple’s Support Community about iOS7 problems)
This system has also been built much bigger than needed so future content and downloading runs smoothly.
The reports also states that Apple has invested over $100 million into the CDN as they hope to control more than just the the hardware. They are set to control how the content is distributed to the devices to ensure the user experience is at a quality Apple is used to delivering.