Barnes & Noble and Microsoft have finalized their partnership agreement that has created Nook Media, a B&N subsidiary in which Microsoft will hold a 17.6% stake. Nook Media, which did not have a formal name until today, will be comprised of B&N’s digital businesses as well as its college stores, and, according to B&N will have a “mutually beneficial relationship with Barnes & Noble’s retail stores.”

The two companies first announced the partnership in April with Microsoft investing $300 million in Nook Media as well as making additional payments that will bring its investment to about $605 million over five years. Today’s announcement did not contain many more details about Nook Media. The college business will continue to be led by Max Roberts, Patrick Maloney and Bill Maloney while Jamie Iannone will head the digital operation. Barnes & Noble CEO William Lynch will oversee both businesses.

In a prepared statement Lynch said: “As demand for digital content continues to increase, we are focused on bringing ground-breaking reading and learning content and technologies to more people in more formats than ever before, including the imminent launch of our exceptional Nook reading application for Windows 8. We look forward to working closely with our new partner Microsoft to add value to their innovative new platform by bringing great reading experiences and one of the world’s preeminent digital bookstores to millions of Windows 8 users.”

“Nook Media is a leader in developing the next generation of digital reading and we look forward to the company bringing one of the world’s largest digital libraries to Windows 8 devices via their upcoming Windows 8 app,” said Andy Lees, president at Microsoft. “We are also excited by Nook Media’s product roadmap and expansion into markets around the world as demonstrated by their recent launches in the United Kingdom.”

The digital assets that are now part of Nook Media include all Nook devices, the Nook Store and PubIt. B&N is also transfering employees tied to those businesses to Nook Media.

B&N said it is still reviewing its strategic options concerning Nook Media, options that include separate Nook Media or spinning if off as its own company.