First of all welcome to the site!
Yeah there is not a lot of info yet since these newer models have only been out since late 2009.
Your best option is contacting your dealer and get the part number for the nav radio and start running that part number on the net. You could buy it from the dealer but I am sure it will cost a ton.
www.gmpartsdirect.com offer discount GM parts.
Your other option is always replacing the stereo with a after market unit but it would be costly as well with all the modules you would need to keep the steering wheel controls and bluetooth abilities.
I have the 2LT as well but 2010. I am pretty content using my android smart phone with Navigation window mount when we go on trips. I know the area I live in pretty well but work landscaping so I use it for finding the job site.