Welcome to Atlanta User Groups John. You may be interested in OWasp for security and Microsoft has multiple user groups meeting throughout the month on all of it's technologies. In fact tonight they are meeting about windows phone development at their headquarters in Alpharetta.
The LUG@GT is the student-run Linux group. Every Wednesday, we have a meeting, usually giving presentations on various Linux-related topics. Anyone is welcome to attend - being a GT student is not a requirement. See the website for more details.See More