Any answer from USCIS call? The same thing happened on my case.

Card/ Document Production

On October 5, 2009 we mailed the document to the address we have on file. You should receive the new document within 30 days. If you do not, or if you move before you get it, call customer service at 1-800-375-5283.

This step applies to applications that result in an applicant receiving a card (such as a "green card") or other document (such as a naturalization certificate, employment authorization document, travel document, or advance parole). Applications will be in this step from the time the order to produce the card/document is given until the card/document is produced and mailed to the applicant. You can expect to receive your card/document within 30 days of the approval of your application.