Barnes and Nobles has just updated their Nook for Android app for all Android devices including tablets, but not including the NOOKcolor itself.
The newest update features better viewing with those on bigger-sized screens, such as tablets (Helloooooo, Xoom!). The update gives you a "grid view" that displays a better view of all your books. A progress bar is added when downloading books and an improvement in adding books to wish lists is another updated feature. Update is available right now in the Market!