As of 2008 (or earlier) any GM dealer should service unexpired extended warranties on Saturns.
I have been buying Saturns from 1997 through 2008 (four cars; still have two) from a local Saturn dealership. It always bothered me that the warranty agreement stated that work had to be performed at the dealer who signed the agreement. In 2008, I was going to purchase a warranty through my credit union, however, I found out that Saturn - always a part of GM; but, with less service facilities nationwide - had changed their policy and allowed warranty work to be done at any GM service center.