AMD always leaves the joys of technology births to Intel and after some time it just jumps on a bandwagon and embraces a new technology, but only after it gets more affordable. They did it with DDR to DDR2 transition, and this time they are doing it with DDR2 to DDR3 transition.
Intel spent a lot of money convincing people that DDR3 was and is a good thing, but it didn’t have much success selling a lot DDR3-based motherboards due to the ridiculous prices of DDR3 throughout 2007 and most of 2008.
Today, you can get a vanilla OCZ 1GB DDR3 value for €35, or 2GB for €70 for both Corsair and OCZ, which is quite reasonable, but still much more expensive than DDR2 prices. This is enough for AMD to go to DDR3 chipsets and CPUs.
We've learned that AMD might be ready with its DDR3 chipset in Q1 2009, and when AMD says this you can only hope it's late Q1 if it doesn’t really get late. The good thing for AMD fan boys and DDR3 lovers is that by Q1 and Q2 2009, DDR3 will severely drop in price by then and it might start becoming a normal thing.
To make things a bit more clear, the DDR3 part of the chipset is actually inside of the CPU, but at the same time these "new" chipsets will be matched with socket AM3 that will enable DDR3 and the new CPUs to work. Of course, the new DDR3 boards will use exsisting Hypertransport 3 marchitecture.
RD790 DDR3 and RD890 DDR3 should be the first two AMD chipsets, boards based on it, to support DDR3.