Based on my testing this morning, although the caching service on OS X Mavericks Server is supposed to cache iOS updates, and although it does a perfectly good job caching App Store content, it does NOT cache iOS 8 itself.
For those of us who manage large iPad deployments (and would prefer iOS 8 to be installed by end-users), this is a problem. Potentially a multiple-terabytes-through-a-finite-pipe problem.
Thankfully the Squid hack I figured out during the iOS 7 launch works with iOS 8 too. Otherwise we’d be in trouble.