RalphJohnson maintains several mailing lists related to patterns. Some have a readership in the thousands.
http://st-www.cs.uiuc.edu/users/patterns/Lists.html mirrored at http://hillside.net/patterns/mailing.htm
See also PatternsDiscussionFaq
WardCunningham announced the creation of this wiki in an InvitationToThePatternsList. Ward also posted TipsForWritingPatternLanguages to the patterns list in 1994.