walkman - 3:09 am on Apr 16, 2011 (gmt 0)
I agree that it seems peculiar for Google spokespeople to suggest all manner of changes and then apparently not re-evaluate sites that have made extensive changes. This is a sign to me that there currently is some limitation on rapid re-evaluation.
In addition, this change also goes deeper into the "long tail" of low-quality websites to return higher-quality results where the algorithm might not have been able to make an assessment before.
This points to a rush job, under the gun of Blekko, the media upset with eHow and the HackerNews kids. This also explains why we lost even more traffic despite the many positive changes: Google never took the changes in consideration.
And 6-7 weeks is long enough not to be called "rapid re-evaluation" :)