Objet announced their "Polyjet Matrix technology", which apparently enables the use of multiple materials simultaneously in a 3D printer. This is a major step, since it will permit the printing of many different kinds of objects - especially those with parts that have different physical characteristics.
Most 3D printers are "additive", meaning they simply deposit layer upon layer - of the same material. Objet's new technology allows mixing of materials so that the depositions are actually different compositions. Imagine a solid printed object that has some rubbery parts, like the grip on a screwdriver, for example. Currently two jets are present in the PolyJet system.