Flash Networks released "..data showing that the amount of network bandwidth consumed by mobile operating system updates can threaten network performance, especially if delivered during peak traffic periods. Based on traffic measured during Mobile Windows and Android updates in Europe and North America, it was found that operating system upgrades sometimes consumed even more bandwidth than YouTube videos, creating significant bottlenecks. This phenomenon is expected to be dramatically increased in the near future by the availability of Apple iOS5 over the air (OTA) operating system upgrades".
I wonder why such updates should not be limited, or configured, to be done when the device is connected to Wi-Fi. Caching could also help - although today it is applicable only on the core network therefore does not help the back-haul congested links.
"After one Patch Tuesday, it was discovered that for a European operator the amount of network bandwidth consumed by operating system upgrades rose from 3.7% to 18.2% of total bandwidth, coming second only to YouTube, which burned up 29.2% of network bandwidth. Similar results were discovered in the US where Windows updates increased upgrade traffic from 4.5% to 20%, an increase of more than four-fold".
See "Flash Networks Releases Data Showing Bottleneck Effect of Mobile Operating System Upgrades" - here