Office hours are different from a regular User Group meeting. They are an opportunity for you to come ask questions about MongoDB. There will be no prepared presentation, so the time is entirely devoted to QA.
5815 Windward Parkway, Suite 302 (on the second floor)
Alpharetta, GA 30005
Drop by the nice facilities of Roam Atlanta on Windward Parkway and meet with Software Engineer Robert Stam.
10gen office hours are held in meeting room #7.