For anyone else interested: Nemo was able to answer this question because
StackExchange has a Quarry <http://quarry.wmflabs.org/>-like public query
interface of their own. You should go play with it right now:
http://data.stackexchange.com/
It's worth pointing out one major difference between their Quarry-like
thing and our Quarry. I love both, btw. But our Quarry suffers because
the only public database we have is raw and has a schema meant for OLTP.
StackExchange's is clearly hitting a well organized OLAP style schema.
Something to aspire to, perhaps collaborate with them on.