GDDR4?

There appeared some informations about new GDDR4 memories, which should be successors to today fastest GDDR3 memories. First chip to be used with should be new NVidia n80. This chip should contain support to Shader Model 4.0. As it was in past, need for bigger, faster and cheper memories should work today in manufacturing memories by new technology. GDDR4 will start on 800mhz ddr (1600mhz) and upper border is unknown. I will tip somewhere about 2500 mhz. But there will be little problem. ALready is known, that GDDR4 technology will be incompatible with older cards, so you cant expect 7800 cards with them.And they should be on market in 2006.