I'm updating two Macs via Software Update in the same network and they share four downloads between them.
Why do they need to download the new versions from Apple? I mean, they could just find each other and swap.
This isn't rocket science, at least not in a system that has Bonjour built in.
And its not as this would be terrible security-wyse: all the updates are signed by Apple and Software Update will refuse to install them if the signature doesn't check.
Oh well, maybe in the next cat.