Thanks deadsea, very similar to what I experienced.
On the surface it appears a very straight forward update and one that can be easily fixed. However in reality that isn't the case.
I too haven't recovered, despite only having one ad on the page. I'm wondering if those sites that cannot seem to recover, actually share anything in common. My suspicion is that sites with low text content above the fold AND an ad (mine is 300x250) are struggling.
It would be useful to figure out, exactly how they're calculating the penalty. (wouldn't it always).