Thanks Pana for your response. In fact, after I have I turned in online the AR11 form related to address/mail change. I got two LUDs on my pending I-140 and I-485. Also, the USCIS sent me a status report about my pending applications in which they confirm receiving my address and mail change notifications. Interestignly, in the I-485 address change notification letter, they mentioned that my Security checks are still pending. In the I-140 address change notifcation letter, they say that I have to wait in line and to watch for the published processing dates online as a guidline on when I might have the I-140 processed.
In anycase, I hope that my I-140 EB2-NIW is pending just for the same reason for everybody else, and not due to Security checks. It is stuck at the notorious NSC. NSC is now processing applications submited one year earlier, August 1 2006. This is just so sick! I do hope that they process my I-140 when I am withing the processing dates, and not have to wait also for my I-485 related security check to clear!