Updated

The lackluster selection in Microsoft's Windows Store has been one of the biggest disappointments surrounding the new operating system, but one missing app in particular has left us scratching our heads for weeks: a Nook app. Microsoft recently bought a big $300 million stake in Barnes & Noble's digital business, and Amazon's Kindle app was there at Windows 8 launch. What gives?

Those questions can now be set aside. This morning, Barnes & Noble announced the availability of a Nook app for Windows 8 and Windows RT devices, and it's already popped up in the Windows Store.

The app pretty much works exactly as you'd expect, delivering the standard Nook app experience dolled up in a fresh new Modern-style coat of paint. The Nook Windows 8 app also sports the same "Paper UI" found in the Nook HD tablet, creating an experience that focuses more on actually reading than on bells, whistles and other extras. The tablet's influence extends even further thanks to the inclusion of the company's new "Nook Channels," a genre-based content discovery engine designed to point you towards books that Barnes & Noble thinks will be up your alley.

Any e-book or digital magazine you've ever purchased through Barnes & Noble's Nook e-store will be available at your fingertips in the app, and it automatically syncs with your e-reader and other mobile apps to ensure your bookmarks and notes travel seamlessly from device to device.  Has it been a while since you've booted up an e-book? The Nook app's Live Tile and "Daily Shelf" feature displays the title you're reading currently as well as any new issues of your favored periodicals.