http://mlb.mlb.com/mlb/tickets/ps_refund_2008.jsp#cubs

Of particular note

INDIVIDUAL TICKETS: Individual ticket holders must send the entire ticket along with their name, address, and daytime phone number to:

Chicago Cubs Ticket Office
1060 West Addison
Chicago, IL 60613

I wonder if anyone can provide any clarification on this but it seems as though in the past the Cubs just issued credits. This makes little sense. Most teams seem to be issuing automatic credits while a few reqiure the tickets mailed back. Anyhow, I had no idea and assumed I'd be getting an automatic credit. So if you're waiting for a refund, make sure you send your tickets back.