It was me, at Subgraph, that setup the Secure Desktops mailing list and website. We hope to collaborate more with other projects in the future. There is already interest from other projects in things we've built for Subgraph.

As for Subgraph in Qubes, being a template OS, etc, maybe later? We haven't even had a real release yet and are still building. I wouldn't recommend it anyways unless all of the Qubes VMs have hardened kernels by default.