No, not really.
As mentioned, there will be performance improvements in 2-way and 4-way server environements, but for the everyday desktop user, hardcore gamer, and hardware enthusiast, the improvements will be minimal; about 10% gain in single threaded applications.
Where Nehalem will shine and be very useful is for the the high end A/V workstation and super-multi-tasker scenarios.
Do not expect the same performance gains that were seen going from the Prescott to Core2 as going from Core2 to Nehalem.