While the contents of the agreement will not be disclosed, Microsoft will receive royalties from Nikon from their use of Android OS.
“Microsoft and Nikon have a long history of collaboration, and this agreement further demonstrates the value that both companies place on responsible IP licensing,” said David Kaefer, general manager of Intellectual Property (IP) Licensing at Microsoft. “Microsoft is proud to align with a leader in the digital camera industry to license Android technology for the benefit of Nikon’s customers.”
It's unclear what the patent licensing agreement covers as Android is an OS developed by Google or which cameras would be affected. Most certainly the "certain Nikon cameras" refers to the Nikon Coolpix S800c (a Nikon Android powered camera) as well as any future releases. Nikon is not the only manufacturer to hook up licensing deals with Microsoft, as Samsung and Polaroid have similar deals in place.
Source: Microsoft News Center