According to my sources, the app now enables readers to browse and sample ebooks without an account. It will also now ping you with notifications about deals in the Nook Store, reading recommendations and more.
The browsing option is an uncommon feature among reading apps, but the notifications s not. Kobo has implemented a similar feature on their Android tablets. (This can be annoying if you don't buy from Kobo.)
And finally thanks to the update the app also now supports annual subscriptions. This last is a rather odd feature to highlight, given the Nook Store has supported subscriptions for at least 3 years now.
You can find the app in Google Play.