The D_S ones (once a month on Sundays, IIRC) have sort of disappeared. I was talking to someone this very weekend about trying to re-start them, perhaps at the replacement for Boloco, which is the Ripe Tomato, or red Tomato or something...

The Meetup.com ones (every other week on Wednesdays) moved to some random room on campus at MIT. But I havent been since them moved because getting to MIT on a Wednesday night isn't worth it for me...