Microsoft on Monday declined to say whether Barnes and Noble\'s Nook app for Metro will be embedded into Windows 8 or Windows RT. Earlier in the day, Microsoft announced it was investing $300 million to acquire a 17.6% stake in a new Barnes & Noble subsidiary that will include the bookseller\'s digital Nook and College business. Microsoft also guaranteed Barnes & Noble additional payments of $305 million over the next five years. As part of the deal, Barnes & Noble will develop a Metro app for the Nook to run on Windows 8 and Windows RT. What Microsoft didn\'t say was whether the app would be bundled with Windows 8 or Windows RT, or would be offered -- along with scores of other third-party apps -- as an optional download from the Windows Store.