I'm on water, a little heat doesn't scare me as long as it's due to blistering performance.
GT200+Nehalem may strain my watercooling loop though, I was waiting for a new GPU before I bought a GPU block... so I've never really come close to stressing the loop before.
Anyway, SMT made Northwood+Prescott rather hot, and that was to run 1 core with 2 threads. Nehalem will be 4 cores with 8 threads, so I honestly expect Nehalem to be an extremely hot cookie when running 8 threads. From what I've seen each core requires 2-thred SMT transistors, so that would be 4x the SMT logic of Northwood... if true, ya see where I'm going with this! Three memory controllers won't help either.
If it lives up to expectations I'll be springing for the expensive LGA1366 version... there are so many disadvantages to the LGA1160 that there may be a very real reason for the "extreme" chip next go around... Not sure if that is a good thing or bad though.