Subgraph has created a new mailing list for Secure Desktop discussions.
Excerpt from initial post:
This forum is the product of a meeting between Subgraph, Qubes OS and Tails, in which it was agreed that we need a place for ongoing discussion of ideas and collaboration in our efforts towards the common goal of building secure open source desktop computing environments. We therefore invite participation from any developers and contributors for these and related projects, including applications, as well as anyone else interested.
https://secure-os.org/pipermail/desktops/2015-October/000000.html
In case you have only looked at TAILS or Qubes, Subgraph OS is a VERY interesting OS design:
Firmware Security 