well this is sort of on topic since we use a fair amount of cement making decorations, edges, stepping stones, etc.
it is good to hear that they are working on finding out how to make cements that do not add CO2 to the atmosphere as much as the current technology for making Portland cement does.
in the current issue of the Smithsonian (Dec, 2011) has an article about someone making cement from magnesium silicate (and other things). the most notable features, it absorbs CO2 and is whiter.
good thing to see, i hope it pans out.
songbird