On March 16, 2012, Charlie Oppenheim, Chief, Visa Control and Reporting at the Department of State, informed that he will likely retrogress India and China-mainland born Employment-Based Second Preference priority dates to around August 2007, effective with either the May or June 2012 Visa Bulletin.
For all I-485 case, the priority date must be “current” when the case is filed, as well as when the case is approved. As such, if dates retrogresses in May, pending I-485 cases that are not approved before May will remain pending until the priority date is “current” again. Since USCIS is taking 3 to 4 months to process recently filed I-485 applications, most cases filed in March may not be approved before the dates retrogress.
Mr. Oppenheim also estimates that all EB-1 visa availability in FY2012 will be used up, resulting in no "spilldown" to EB-2.