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Wikipedia subsection on the subject.
It should also be noted that the applications that benefit are ones that would generally be used in Xeon (server and workstation) machines. Further, most of the applications that failed to benefit from hyperthreading are not written to take advantage of many (more than one or two) cores. As applications are updated for "many core" systems, it is likely that the benefit from hyperthreading will become more significant.
In any case, it is far from "established" that hyperthreading has "no benefit."
I was talking to a parent at the free skate while they were resurfacing the ice (they resurface before and after the skate, and once in the middle) and he was saying that he would be back at 6am for his kid's hockey practice. 6am - 2am, resurfacing at least once an hour.
Frankly, I think the 12-15 times a day estimate was conservative, and that the number is probably closer to 20.