Engineers say Sony R&D cash went into the Xbox 360's CPU

When the companies entered into their partnership in 2001, Sony, Toshiba and IBM committed themselves to spending $400 million over five years to design the Cell, not counting the millions of dollars it would take to build two production facilities for making the chip itself. IBM provided the bulk of the manpower, with the design team headquartered at its Austin, Texas, offices. Sony and Toshiba sent teams of engineers to Austin to live and work with their partners in an effort to have the Cell ready for the Playstation 3's target launch, Christmas 2005.

But a funny thing happened along the way: A new "partner" entered the picture. In late 2002, Microsoft approached IBM about making the chip for Microsoft's rival game console, the (as yet unnamed) Xbox 360. In 2003, IBM's Adam Bennett showed Microsoft specs for the still-in-development Cell core. Microsoft was interested and contracted with IBM for their own chip, to be built around the core that IBM was still building with Sony.