I just signed up and looked around the site. But I don't quite understand the platform. Is the Nook an eReader that happens to also be an android tablet? What does the Nook SDK provide? I didn't see any docs on the site.
Yes, the Nook Color is essentially an android tablet. Along with eBooks, book store, and web browsing, it has an "Extras" area which currently features a limited selection of apps (Pandora, photo gallery, crossword, chess, sudoku, mp3 player). Barnes and Noble will be launching a moderated version of the Android App store (along with Flash capabilities) in an update sometime this month.