[Groxx]

...there was no indication that if you tried out the feature, a list of people that you e-mailed frequently would be published to the public.

Yes, there was. After your first attempt to post, this popped up (this is the original, not the newer one(s)): http://img694.imageshack.us/i/buzzflaw.jpg/

Note that it says "name, photo, people you follow, and people who follow you", while using the word "public" several times. Clicking "edit" let you uncheck the "people you follow / follow you" box that's since been made more prominent and on that popup.

edit: bah, static-link fail. Updated link. Original source: http://is.gd/8Fduj