From the Adsense blog:
"Keep in mind that currently, all CPM ads are site targeted, ..."
I wish that were still true! Also I wish we could turn off CPM just to see what happens.
In the past Adsense kindly did turn CPM off for me and for periods of 10, 30, and almost 60 days before and after this change, EARNINGS after Aug 18th 2006 were consistently UP approximately 40%. What's your Adsense "Classic"