I guess this is old news to everyone else, but new news to me. Apparently this was first reported back in late February, and the story still seems to have legs. For example, here is what the ETNews/Korea IT News is reporting about Samsung (and Apple) :
According to industry sources, the next flagship phones of the companies are expected to adopt unprecedented materials for their main bodies, that is, ceramic for the Galaxy S3 and liquid metal for iPhone5, both being thin, light and highly resistant to external impacts. The new phase of the rivalry is because neither one of them can get a decisive edge over the other solely with its OS and AP specifications, features or design.
The Galaxy S3, scheduled to be unveiled in London in May 3, is known to have a ceramic main body. The material is made by applying heat to a non-metallic inorganic substance. High-tech ceramic using silicon nitride is extremely light and comfortable to grip.
I suspect the “liquid metal” reference is actually about Liquidmetal Technologies, a company that has novel amorphous metal alloys. The company reportedly has been working with both Samsung and Apple.
CNET also is also reporting about the Samsung ceramic case.
ADDING: CMS Wire is also chiming in and suggesting that Apple may do something new with glass for the iPhone 5.