Samsung will pay Microsoft for running Android.

This development brings to two the number of major Android OEMs from which Microsoft stands to collect royalties - Samsung and HTC. The third OEM, Motorola, has just recently been bought by Google.

In its website, Microsoft announced on Wednesday that it has signed a "definitive agreement with Samsung Electronics Co. Ltd., to cross-license the patent portfolios of both companies."

"Under the terms of the agreement, Microsoft will receive royalties for Samsung's mobile phones and tablets running the Android mobile platform. In addition, the companies agreed to cooperate in the development and marketing of Windows Phone," the Microsoft information says.

"Microsoft and Samsung see the opportunity for dramatic growth in Windows Phone and we're investing to make that a reality," said Andy Lees, president, Windows Phone Division, Microsoft. "Microsoft believes in a model where all our partners can grow and profit based on our platform."

"Through the cross-licensing of our respective patent portfolios, Samsung and Microsoft can continue to bring the latest innovations to the mobile industry," said Dr. Won-Pyo Hong, executive vice president of global product strategy at Samsung's mobile communication division.

Microsoft ends its press release with Dr. Hong, saying, "We are pleased to build upon our long history of working together to open a new chapter of collaboration beginning with our Windows Phone "Mango" launch this fall."

To Android watchers, this news confirms one thing: Android is not free.