Intel revealed that it is using two new materials to build the insulating walls and switching gates of its 45 nanometer (nm) transistors. Hundreds of millions of these microscopic transistors – or switches – will be inside the next generation Intel® Core™ 2 Duo, Intel Core 2 Quad and Xeon® families of multi-core processors.

Intel is the first to implement an innovative combination of new materials that drastically reduces transistor leakage and increases performance in its 45nm process technology. The company will use a new material with a property called high-k, for the transistor gate dielectric, and a new combination of metal materials for the transistor gate electrode.
"The implementation of high-k and metal materials marks the biggest change in transistor technology since the introduction of polysilicon gate MOS transistors in the late 1960s," said Intel Co-Founder Gordon Moore.

Intel already managed to build the first working 45nm Penryn code-named processors.
More details in this Intel press-release.