GITenberg has a mailing list: https://groups.google.com/forum/#!forum/gitenberg-project

And there has been some conversation about the project on the OKFN-humanities list: https://lists.okfn.org/mailman/listinfo/open-humanities

OKFN is organizing a skype call about the project on the 1st of September 6pm UK time that will be announced on the humanities list in the next few days.