Regardless of the fact that Randfish says he made a mistake at SEOChat, I can vouch for the man's integrity and ability to understand the nearly impossible.
At the NYC SES Conference, I sat in the front row, in between Rand to my left and Bill Slawski, to my right, pretending to understand Dr. Garcia's (aka "Orion's) power point presentation on search engine algorithm technology. My eyes glazed over exactly the way they used to do in Math class.
Meanwhile, Bill and Rand were muttering outloud various things that convinced me that I was sitting between two geniuses. They understood the diagrams on the wall.
Rand, though admitting he may have said something erroneous, still understands C-indexing, and in his SEOmoz post today, points to some resources on term vectors, on-topic analysis and the mysterious and anal world of keyword density. Go there now, and read it all in the privacy of your own home or office cube, where nobody is watching to see if you really know what the heck all this stuff means.
I won't tell.