Use search term "rear wiper" off the home page from upper right of the saturnoutlookforum and do the same on acadiaforum. You will find plenty of results on rear wiper replacement how-to and retail locations that stock the parts.
This thread may start you off (follow any links therein and note part numbers along the way). Saturn dealers carried BOSCH Icon blades, these effectively were the OE part and performed great - but they're more expensive than your average generic refill. Trico may be a cheaper alternative.
I have yet to replace the wipers on my '09 Outlook XR. I did replace the blades on my Pontiac Pursuit (aka Cobalt / G5) and I obtained Rain-X Latitude from Wal-Mart. They've been great and even handled a mild Canadian winter despite not being a "winter" blade. I bought the Rain-X blades based on recommendations on the above noted forums. When it comes time to replacing the blades on my Outlook, I'll be doing BOSCH Icon's again as they've been performing very well too.
