Yes, the jam is happening this Sunday, September 1st. The tune for this week is On Green Dolphin Street. It is important to note we are playing it in Eb. To help with your preparation here are a few links and a video of a famous version by Miles Davis.
Chord charts and free play along: http://www.learnjazzstandards.com/jazz-standards/on-green-dolphin-street-in-eb/
Background info and analysis: http://www.jazzstandards.com/compositions-0/ongreendolphinstreet.htm