Today my NG, the NOOK I keep in my purse, died--DIED. It could not be turned on or turned off; the opening "tree" screen was constant. I was a few blocks from B&N when this happened, so I dropped in. B&N personnel at my local store verified my problem and tried plugging my NG in to see if that helped. It didn't. At that point when B&N tried to turn it on/off again, the screen developed those strange striations in the background and B&N declared it officially dead. They gave me a new one.
When I came home, I registered the new NG immediately and checked the settings to see if this were an older boxed unit which might need a software update. The B&N support page for NG lists the latest update as 1.2.1. My new NOOK, however, shows software version 1.3.1.
I also checked the settings for my NST, which I was updated to the latest version. The NST shows version 1.2.1
The NST version and the NGL versions are different. I *think* 1.3.1 is the latest for the NGL. In any case, if you turn on wifi and leave it for a bit, if there is a newer version it will probably update on its own.
II just checked my Nook Glowlight and it is version 1.3.1. As Keriflur said, the Nook Simple touch Glow and the Nook glow are different.