Just got another case status change:
"On September 13, 2013, we mailed the new card directly to the address we have on file. You should receive your new card within 30 days. If you do not, or if you move before you get it, call customer service at 1-800-375-5283."
Woohoo! I've heard USCIS mails it with 2-day shipping, so I should get it early next week. Can't wait!