ZDNet Asia reports that in the agenda of the upcoming International Solid State Circuits Conference (ISSCC 2007) in February a new 6Ghz Cell Chip will be discussed.

The new CELL Chip will be made in 65nm CMOS SOI technology and a dual power supply. If this new faster CELL Chip will make it into a new Sony PS3 is only speculation at this point.
Quote from the agenda (pdf):
"The 65nm CELL Broadband Engine™ design features a dual power supply, which enhances SRAM stability and performance using an elevated array-specific power supply, while reducing the logic power consumption.
Hardware measurements demonstrate low-voltage operation and reduced scatter of the minimum operating voltage. The chip operates at 6GHz at 1.3V and is fabricated in a 65nm CMOS SOI technology."

Toshiba, IBM and Sony revealed the current CELL Chip in February of 2005.