Hi Keith,
The official repository of OpenACS is still the CVS repository at openacs.org, but it is mirrored at a daily basis to github. The openacs github mirror can be used for tracking changes (with a maximum one day time lag). i've updated the state openacs-on-git on [1].
We are at our university currently in the process of updating all packages to new versions. Our acs-core is pretty new, but many application packages are still on 5.2 and substantially modified. In this process, we are rebasing the code from our own git repo to a structure based on the github history to ease future updates (Héctor is doing this work).
all the best
-gn
[1] https://openacs.org/xowiki/git_migration