They have been working on it for a while, apparently, you can try it right away http://docs.mediagoblin.org/siteadmin/deploying.html

There are also public instances[1] such as gobblin.se[2] which i own and administrate (beware of bugs, gobblin.se is tracking git master which means it is very bleeding edge).

[1]: http://wiki.mediagoblin.org/Live_instances

[2]: http://gobblin.se