ATI's new flagship performance and high-end chips will have the ability to use GDDR5 memory. This is the next big thing that ATI plans to embrace.
It looks that GDDR4 didn't really hit it off well, as it doesn’t bring a lot of advantages over GDDR3, but GDDR5 promises some crazy frequencies all the way up to 2.5GHz / 5GHz effectively, which is more than two times faster with what you can achieve today with GDDR4.
This means that the new memory will have more bandwidth and this is something that graphics cards always enjoy.
At this time, we are not aware that GT200 has GDDR5 support.