The Design Patterns Study Group of New York
City has been meeting weekly since August, 1995. Back then, there were no public patterns discussion groups. Our meetings are for both advanced and beginning students of patterns and pattern languages, and we always
welcome new members. 
Our study group now consists of four sub-groups: the PL (Pattern Languages) Group, the GoF (Gang-of-Four) group, the 4G (4 Gangsters) group, and the newly added AP (Analysis Patterns) group.
The AP group is, to the best of my knowledge, dormant.