For many years, Intel has downplayed the advantages of having integrated memory controllers and direct links between CPU cores that AMD has been implementing. After the “death” of Hyperthreading, they continue to push FSB higher and assumed all would be well. It wasn't, however, and the incredible performance and growth of the Opteron proved it. They have learned, however, and with Nehalem, Intel will be introducing many of those features. On top of bringing back Hyperthreading, they'll be making their new modular processor capable of using an integrated memory controller and allow its internal cores to communicate directly. The modular design of Nehalem means that not all CPUs based on it will include these:

Not every chip in the Nehalem family will come with all those features, but they will be available to Intel's designers, Gelsinger said. Different customers require various types of products for their future PC and server designs, he said.
It'll also give Intel lots of room for expansion, such as the ability to add different types of integrated controllers into the CPU design. All Nehalem chips will be based off the upcoming 45nm process and are expected to be here in 2008.