SiS isn't typically a company that brings bleeding edge technology to market, most particularly with chipsets. Often, after other companies have finished with the first wave of development (such as Intel and nVidia), other companies begin to refine their versions and start to ship. SiS is looking to get a bit of a leg up, however, with the SiS672 and SiS772 platforms, which will be SiS's first chipsets to support DDR3 SDRAM. These new chipsets will be available in a little over a year from now, not far long after Intel has plans to release their own DDR3 chipsets.
Produced using an 80nm process, the SiS672 is designed for Intel processors (probably Core 2 revisions) and the SiS772 is designed for AMD processors (probably AM2 successors for DDR3). While complete feature sets are hard to bring out this early in the game, you could probably expect a standard full feature set when the samples start rolling out next year. Depending on how receptive the market is to DDR3, we may see DDR2 as one of the shortest lived memory standards the market has seen. On a side note, it seems that the next generation of SiS chipsets will support Opterons, but not Xeons. Very interesting.