http://www.immigration-law.com/Visa%20Retrogression%20Q%26A.html
Q: I am a Chinese waiting for EB-485 approval. I married to a Chinese woman four months ago. She is in a F-1 student status. She could not file I-485 because the my visa number was retrogressed. But beginning from August 1, 2006, my visa number became available. I wonder whether she is eligible and where she should file her I-485 application.
A: Your wife is eligible to file her I-485 application as accompanying derivative beneficiary of your employment-based petition, provided that she was married to you before your I-485 was approved and the visa number is current for you. Accordingly, even if the Service Center approves your I-485 tomorrow, she will still be able to file her I-485 application based on your approved employment-based petition and your priority date. This would have been unavailable, had you married her after the Service Center approved your I-485. As for the USCIS office where she should file her application, since last monh, July 2006, the USCIS has centralized the employment-based I-485 filing for the derivative beneficiaries into Nebraska Service Center. Accordingly even if you filed your I-485 application in Vermont Service Center, your wife should file her I-485 application with the Nebraska Service Center attaching your approved I-140 petition and I-485 Receipt Notice. Within the USCIS, your I-485 and your wife's I-485 files will be inter-filed and processed together. The bi-specialization process is currently causing a lot of confusion as related to the filing procedure, but you will have to live with it until the USCIS filing system is more stabilized.