This is certainly a next gen technology for the MP. The current '08 only takes DDR2. The referenced article is talking about a DDR3 modules.
We all know that faster DDR2 memory is compatible with slower DDR2 and vice versa e.g. you can put the 667MHz stuff in the new '08 but it will run at the slower speed. However, DDR and DDR2 are not compatible - different notches in different places / different pin densities, etc.
Now for the next MP, especially running Snow Leopard that bad boy could theoretically accomodate 128GB of RAM.
Someone correct me if I'm wrong, but aren't we edging closer to where someone could load their entire OS and all their programs into RAM and basically ditching their need for their hard drive? Like in 5-10 years we could be talking about 256GB - 512GB of RAM!