I'm surprised that the only tool for automated configurations mentioned (very quiclky) in that thread seems to be puppet... and is only mentioned as "the poor man's puppet".
I am personally quite interested in that topic, which is why I am (slowly) building my own debian installer, of which having an acceptable PXE configuration is only the 1st step (it's not good enough for me), and I have found various tools to achieve that goal, that I would split in 2 categories, each having different contraints:

* agent-based tools, which usually derive from cfengine, which agent is written in C (puppet being one of them). They are (probably) great when you are actually admin of the targets, and have the right to install stuff. They (should) allow a system to auto-repair or to inform it's administrators about the derive from the repository from which their configuration is derived
* independent tools, which seems to all be some fashion of interpreted language. I know more about rexify, which is written in perl, there are some in bourne script, but the most well known nowadays seems to be written in python.

I don't really think a package manager can do the trick here, not alone at least, you'd need some way to trigger it, and a cron tab for updates will just break stuff at a moment or another, except if you own your repo and validate the packages you put there, but that's a lot of work