Whitey - 1:12 am on May 31, 2010 (gmt 0)
I've been observing sites that have used either keyword specific URL's and / or keyword specific navigation of more than three words to form good rankings in the long tail.
From Google's point of view , there may have been a perception of " manipulation " in the results that came from these and in many instances it didn't always reflect in the quality of the content. If this theory is correct , then maybe Google considerd that it could do a better job of deciding what those pages were about.
So could it be that Google's data matching capability that better analyses on page content and other signals has overtaken these tactics , or at least weakened them , as one element of the change ?