User blog comment:Dopp/Technical Update: March 14, 2011/@comment-876022-20110315024535/@comment--20110315153913

ScavengerHunt, like Chat, is something we are testing and releasing bit by bit. Major new features, as always, will be announced on the Staff Blog when they are ready for either beta testing or release.

And yes, Automatic Wiki Adoptions was the cause of the emails.