You have marketing, advertising, internet advertising, search advertising, pay per click, contextual ads, and then AdSense. It is rare to find someone who is a specialist in SEM, but to find someone who knows pretty much everything there is to know about AdSense - is just amazing. I strongly recommend that when you see Jenstar posting at WebmasterWorld or at Search Engine Watch Forums, that you take in every word.
Jenstar's latest thread at WMW is named Analysis of how US Thanksgiving affected AdSense earnings. In that thread, she shares some of the data she collected from her AdSense reports:
Total earnings: Down about 33% Impressions: Down about 65% CPM: Up about 25%
The rise in CPM *really* surprised me. I guess people were hoping to get an early start on the biggest shopping time of the year. Most holidays show that CPM drops off significantly as people lower bids or pause campaigns for the holidays. If only my impressions were at their normal levels, I would have had an extremely good day.
Jenstar knows the AdSense rules inside out and she is one of the brightest when it comes to contextual advertising at the forums.
Update: Make sure to check out her blog named JenSense - it's all about the AdSense & other contextual advertisers too. Wow a blog on AdSense mostly.