The next generation Roewe 750 will be based on the platform of the China-made Buick Regal. The Ragal is made by the Shanghai-GM joint venture. Shanghai Automotive Industry Corporation (SAIC) is also the owner of the Roewe and MG brands. This means that the next generation MG7 will very likely be based on the Regal-platform as well.
The Regal is basically a rebadged Opel Insigina, the Roewe 750 a rebadged Rover 750. The deal makes most sense for SAIC. Not much for GM because it only helps the competition getting better. The new 750 will debut late 2011.