Nehalem can and will get to 45nm. This is something that hasn't really been communicated that clearly, but now we can confirm that this is the plan.

Westmere, Nehelem's successor at 32nm, will naturally also get to eight cores, but even at 45nm Intel can get to this quite unique product to market.

As you know, AMD has troubles releasing its 45nm quad-core, not to mention the eight-core, and today Intel is actually producing 45nm CPUs for about a year, while the competition didn’t even start.  

The big problem will be to get enough performance out of the eight-cores, which won’t be a bit of trouble for the server and workstation market, but the other market segments will have a tough time fully adopting it. This is why more than 8MB cache will appear in the new CPUs.