Sorry for the two posts today :P
But, my case status just updated (again) a few minutes ago. It's the one I've been waiting for:
"The USPS reported that they picked up mail from USCIS containing your new card on September 13, 2013. The USPS tracking number assigned is #########. You can use this number at www.usps.com to view updates to the delivery status of your mail. You should receive your new card within 7 days. If you do not, or if you move before you get it, please call our customer service at 1-800-375-5283."
Yay! Now I can properly track my green card! Expected delivery date is this Monday. I'm pretty much going to pounce on the mail lady when she gets to our apartment building, lol.