I hate to nitpick with this kind of thing, but I am a little curious whether the CPU utilization percentage results they report in some of the tests are relevant. That is, does a pair of logical CPUs report its utilization in a way comparable to the utilization reported by a processor with a more traditional setup? I've seen dual Xeon systems where the two primary logical processors are pegged to the max (say with, heh, Folding), and the two secondary logical processors are idle. Both Xeons are actually quite busy, but the max CPU utilization reported doesn't go much past 50%, because two logical processors are unoccupied.
Anyhow, interesting article. Check it out.