While jigbo is better than full downloads of respin images, on fast moving releases I find that there are still a boatload of changes to make after only a few weeks. I wind up doing a Unity install from a recent respin, and then mounting a repository of recent upgrades and updating again.
Since I have to burn a repository DVD before going to do an install, it would be nice if there were an easy way to just generate an update respin of my own, with just the updates we have done in the office (not maintaining a full rsync mirror).
I have the feeling that there should be such a way, and that someone is way ahead of me on this, the "Live CD" stuff doesn't seem to be quite what I want, I need to update the most recent respin with whatever any system in the office has saved in its yum cache, and make an updated install DVD.
Note: I do installs in places with poor network connections, install from a DVD or even the CD set, is the practical way.