SC54HI

If she has an "IOE" in front of her USCIS number (meaning her application was made using the newest form), that's probably why nothing appears to have happened. The IOE forms require use of a new software or processing system (ELIS) and not all field offices have rolled out this update or are trained on it. Also, the IOE applications are being sidetracked, apparently, so as to allow USCIS to process all of the applications made using the older (NBC) forms. Adding insult to injury, apparently the newer ELIS system does NOT update the online account for every USCIS action, such as being in-line for an interview. There is finally some movement, though, on the IOE applications, with interviews being scheduled at several of the busier field offices in the US.
There is an extensive discussion on another immigration forum about this matter: http://www.trackitt.com/usa-discussion-forums/n400/1655760285/reciept-number-starting-with-ioe. If you read there, you should get a better idea of what's going on and what options you might have for an inquiry on your wife's case status.
Best of luck!

Thank you -- these are good ideas & spouse will do this.
Spouse talked to helpful individual at the 800 number on the notice. The CSR could only recommend trying an early walk-in as well although they also said that he could resubmit for a new appt. Since spouse has the time & ability, early walk-in it will be.
Thanks again to all!