Processing date as published in the USCIS processing times web site indicates the median Receipt Date for the application. So if your RD is earlier than the processing date then your case is probably being worked upon. If the above condition persists for 60 days or more then you can call the service center.
By the way August 16, 2007 was the last date for July 2007 visa bulletin applicants. TSC is still processing the July 2007 RD cases (as per July 15, 2008 update). So if TSC processed as per RD, then your case is yet to be processed (my guess).