A brand new expensive one that isn't compatible with any of your current hardware is what kind of mobo it will need. I love the people that think Nehalem is going to be a kick @ss CPU or even a kick @ss gaming CPU. Nehalem could be a complete flop laden with issues. At the moment, the best gaming CPU is a dual core. Do you really think games are going to jump up to utilize 6 cores by the time the first ($1K) CPU appears? Penryns will be going strong even into 2010. Intel will come out with new steppings that increase stability and multipliers just like the Q6600s and your precious 775 socket that everyone is telling you will be dead by 09 will still be alive and kicking and quads will just be reaching their pinnacle. Keep in mind, quad cores are not even mainstream yet.
Seeing how long quad cores have been around, the fact that X38/48 JUST came out, and coupling that with the fact that there are still 775 chipsets to come out (P45)...Nehalem will take off as graceful as Dumbo.
The only way that Nehalem will work for gaming is if Larrabee is working well and accepted by developers. Then, and only then, you will see a need for more than 4 cores any time soon. Intel knows this is a gamble so that is why they are still developing new chipsets for 775 socket. They need that safety net. This is all part of a drunken tirade however, so cheers to the death of 775 mates.
Edit: Furthermore, Intel is going to create an even worse stagnated market for their 45nm quad cores by trying to focus on selling $1k Nehalem CPUs. This will allow AMD to finally catch up and perhaps surpass the 45nm quad core performances since Intel will be split like the Red Sea. This is a huge risk for Intel because it all rests on ray tracing's shoulders.
One can even compare this in parallel with the release of the X48 chipset. Incredibly useless since X38 just came out 3!!!! months ago AND board makers just ramped up the X38 specs that were supposed to be specific to the X48's. At this rate, people will still have 45nm quads on back order when Nehalem comes out. It will be a marketing train wreck when Intel releases a dual/quad core Nehalem.