My spouse's 485 got the same message (a dependant on my application) and 2 different emails, one said
"Current Status: Notice returned as undeliverable.
On January 10, 2007, the post office returned our last written notice on this case as undeliverable. This can have serious effects on the processing of this case. Please call 1-800-375-5283 to update the mailing address so this notice can be re-sent.
If you have questions or concerns about your application or the case status results listed above, or if you have not received a decision from USCIS within the current processing time listed*, please contact USCIS Customer Service at (800) 375-5283."
received another one after 8 hrs
"Current Status: Document OTHER THAN CARD manufactured and mailed.
On January 10, 2007, we mailed the document we manufactured based on our earlier approval of this case, and mailed it to the address on 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."
called USCIS and the rep repeated the same content.
I don't know what's happening, will keep you poste.