xiaobaitu,
I updated my address on line with USCIS and informed them about to change mailing address on my pending I-485 case (employemnt based) as well. However it seems like it takes 1 month for them to update my address in their system after they receive the on line request.
I am concerning that if my I-485 get approved before they update, green card and approval notice might get lost when they mail them to my old address. In case it happens, Can i go to the local office to get a stamp on my passport for travel purpose? Thanks!