On October 2, 2013, GNU social developer MMN-o (Mikael Nordfeldth) published a blog piece announcing that they'd rolled out a change to their WebFinger implementation, adding backwards-compatible support for the RFC7033 version;
"Plus of course the former RFC6415 (Web Host Metadata), which StatusNet supports (but only XRD format)."
For those who don't know, masrodon.social was created to federate with #GnuSocial servers.