So the Ubuntu community, and some of its leaders, have embraced ubuntu.SE so well that it's now an impressive success. Is there a distro (or some other Unix/Linux community) that (semi)officially recognizes and promotes unix.SE?
Sadly, no distros or major *nix communities promote us. AU is a special case; as far as I know no other SE site has "official" support like they do, so I wouldn't worry too much about it. I'm fairly confident that's also the reason we didn't end up getting force-merged with them back at the beginning; their semi-official recognition from Canonical is a big deal
Speaking from a "Stack Overflow Inc" point-of-view, we have not been approached nor heard of any other distro embracing or asking for any sort of official support through unix.stackexchange.com as Canonical/Ubuntu initiated.
I do not believe unix.SE needs an official sponsor. Actually, this may be a bad thing if only one or two distros officially moved their support on unix.SE: imagine if 50% of the questions were about gentoo, or opensuse, or XYZ... I would feel less confident to ask a generic unix/linux question.