In the attachment you'll find the links to Windows Phone 8 update packages. So far, I haven't done much research on it. I haven't looked into possibilities to flash these packages to Windows Phone 8 devices. For now, the download-links for these packages are only meant for research-purposes.
The GDR2 update for the NOKIA Lumia 920 consists of a total of 498 cab-files. These files are OS update-packages and driver packages from NOKIA and QUALCOMM. There are a lot more cab-files than in the Windows Phone 7 updates and the files are much smaller. The update is probably split up into many small packages for better performance of OTA updates.
Added GDR1 updates (captured by AlvinPhilemon)
Added GDR3 updated