Nearly two years ago, Sony announced a joint plan with IBM and Toshiba to further the development of microprocessor technologies. The crowning achievement of the trio, the Cell, has been lauded by many as a revolutionary processor in its time. And even though it is the Cell that powers their "revolutionary" new console, Sony has announced that they are stepping down from the joint research endeavors and will be selling off their R&D assets to Toshiba.
They aren't getting out of the game altogether; they still intend to work with the trio for processor development, but as far as future research goes it seems they have given up the ghost. The exact reasoning behind the withdrawal isn't mentioned, though perhaps Sony feels they are not getting a strong enough return on investment to continue doing research.