The fastest 65nm X2's i've seen f/s thus far are 3600+/3800+ X2's. Which both of those you can be sure are coming with the normal aluminum hsf.
They are running VERY cool with those hsf's though. It appears that these cpu's are hitting 3+ghz fairly easy from some of the reviews i've seen. I am not sure if the stock hsf would be good for 3+ghz though.
Jason