Update: Recd. my interview notice.
Interestingly, my wife's notice came from the Boston DO and didn't have the "USCIS letterhead" (like it was a photocopy of the notice of action with the top few lines blanked), however mine came from NBC Missouri and was on the usual letterhead.
Self
D/O : Boston, MA
10/27/08 : N-400 Mailed to VSC
10/29/08 : N-400 Recd. by VSC
10/30/2008 : Received Date / Priority Date
11/01/2008 : Notice Date
11/03/08 : Check Cashed
11/06/2008 : Received I-797C, transferred to USCIS National Benefits Center
11/12/2008 : Received FP notice
12/04/2008 : FP Appt. (Completed)
12/22/2008 : Interview Letter Received
01/29/2009 : Interview at 7:30 AM
Spouse
D/O : Boston, MA
10/27/08 : N-400 Mailed to VSC
10/29/08 : N-400 Recd. by VSC
10/30/2008 : Received Date / Priority Date
11/01/2008 : Notice Date
11/03/08 : Check Cashed
11/06/2008 : Received I-797C, transferred to USCIS National Benefits Center
11/12/2008 : Received FP notice
12/04/2008 : FP Appt. (Completed)
12/20/2008 : Interview Letter Received
01/28/2009 : Interview at 2 PM