Specifically, if I have a small virtual LAN with multiple VMs of each different distro - say three CentOS VMs, two Debian VMs, and assorted Ubuntu VMs - can Squid safely cache the updates for each with out interfering with one another?
I'm aware of squid-deb-proxy for Ubuntu, but I'm looking for something a little more general purpose - I think.
Well... for what its worth: yes, Squid can easily be used to cache updates for RH-based distros such as CentOS, Fedora and Scientific Linux.
All that is required after initial setup of squid on the server itself is to point the client machines at the server by editing /etc/yum.conf and adding a line at the top that reads:
(insert ip/port numbers appropriate for your setup).
Some additional fine-tuning of squid may be desired in order to adjust the disk cache size, retention times, etc.