The guys over at AnandTech have an article today on what to expect from Nehalem
As IDF has started, the first benchmarks of Nehalem will probably pop up. It is without a doubt an impressive architecture that gets a much better platform to run on, but this CPU is not about giving you better frames per second in your favorite game than the Penryn family. …Nehalem is about improving HPC, Database and virtualization performance, much less about gaming performance. Maybe this will change once games get some heavy physics threads, but not right away.
…But that doesn’t mean Intel made a bad choice. Intel made a superbly good choice by improving the performance where Core (Merom/Penryn) was mediocre to good. Penryn was already a magnificent gaming CPU, but it could not beat the AMD competitor in HPC benchmarks. And AMD gave good resistance in the database performance benchmarks. That is all going to change.