That specific plant was sold by Sony to Toshiba in 2008.
http://www.electronista.com/articles/10/12/22/sony.to.buy.back.toshiba.cmos.plant.for.600m/
Now that they have proven Cell is a viable solution for number crunching systems, Toshiba no longer needs to bury itself in managing its production.
Seeing how many chip manufacturing giants have separated their departments into concise brands, Toshiba will push towards the same corporate behavior. Such was Motorola with OnSemi and Freescale, Philips with NXP, and so on. It is a move by corporate folks to quantize their benefits/percentages. I can only see benefit in segregating departments into separate brand names for the sole purpose to provide assurance that the company brand will not fall over by a lawsuit, stock deflation or any licensing infringement.
Toshiba is a plethora of products in many fields, from washing machines to IC manufacturers. They practically live in your home. Also, they have always been pioneers in the field of electronics and had little feedback from the market, i.e. HD DVD superseded by blueray, and now with ssd proving to be quite a challenge.
The move to source Toshiba materials from Samsung is not without merit, Samsung products are cheap. While Samsung may handle the final assembly and mass production, Toshiba or whatever new brand that may handle the entertainment branch will still be the brain force as Toshiba will be the sole designer of whatever goes into the silicon.
Comparing Toshiba to Samsung, Samsung has never pushed forward to new technology rather than just apply what is in the field.
