It took a FOIA request to get the list (which should be published on the FAA.gov website, but isn't).
Here are the non-Federal (private and/or local government airports) Commissioned AWOS sites sorted by state and city (PDF) -- Commissioned AWOS sites .
Note: this pdf was prepared by scanning and OCR'ing the paper copy received from the FAA in April, 2010. There may be additional sites that were added since April, 2010.