The company took the original PCB design of the XPERT modules and changed the design so that new heatsinks could cool the memory modules not just by cooling memory chips - but the PCB itself is now part of the equation.

The new heatsink design enabled the guys to clock the same chips as the ones in the 8500C4 - up to 1.25 GHz clock, surpassing the 10GB/s per module barrier. Which in current AMD situation end up with 20 GB/s of raw memory bandwidth? Intel is snagged at 12.8 GB/s by a front side bus, but you should not forget the fact that these modules will significantly improve the write speed of the system memory, not just read one.
The product should be available on the market in the next couple of months.