This really isn't any news, to be honest. The 40D posted similar results against the K20D, and in the noise test, even did a little better than it's replacement, the 50D.
The difference is because of how the PRIME engine tackles noise reduction. Rather than smearing away all the noise (and subsequently a lot of detail as the ISO goes up), Pentax cameras seem to leave a lot more chroma noise behind, but also a lot more detail in the process. In absolute overall detail, the K20D trounces all the cameras they've compared it to. The problem here isn't the overall detail resolved, but the noise level. For a lot of people, the noise exhibited by the K20D would be termed unacceptable. However, this is a personal preference. They don't come out and slam the other brands for dropping so much detail at higher sensitivities, but you can tell by the K20D review that they were impressed by the way the K20D dealt with noise control, even if they didn't accept it with open-armed admiration.
Saying the Pentax kicks ass in detail resolving at high ISOs and the other manufacturers could learn a thing or two from them would be a real good way to start a flame war with their readers, so naturally, that topic isn't addressed.