Nehalem will not only be a native dual, quad and octo core design, at the same time  it will have some new instruction set called SSE 4.2.

Penryn supports SSE 4.1, the whole 47 instructions, but it seems that SSE4.2 and Nehalem will support an additional seven.

This is the only instruction set that Intel wants to support in 2008 and we are sure that it works on its own way of SSE 5 or however it will decides to name it.