Got I-485 Approval email this moring. Special thanks to 83211, Pjing and Xiaobaitu.
This is really a long journey. I finally got my Green Card thirteen years after I came to US.
My PD date: Jan. 11, 2006
I-485 Receipt Date: Sept. 12, 2007
Finger Print Date: July, 2009
Service Request: Aug. 17, 2010
By the way, I changed my employer in March 2010 without filing a AC-21 letter with USCIS.
Good luck every waiting one.