There was a flood of reports over the weekend by Google AdSense publishers complaining their AdSense earnings was as much as 50% lower than the estimated earnings they were projected to earn for the month of October.
We have threads at WebmasterWorld and Google AdSense Help with complaints of the major earnings difference. Here are some select complaints:
Yes, I just noticed the same for myself. The estimated earning for Oct where on par with how it has been for the past 20-30 months, but the finalized earnings are way lower. Only 56% of the estimated report.
Same here. earnings of $927 and they say finalized earnings of $292
For October i see in Payments an amount with -20% lower than Estimated Earnings. Also, in main interface of Adsense Last Month shows the correct amount (not lowered with -20%).
I personally checked my earnings and they are pretty much the same as my estimated earnings. But there are tons of reports of huge differences between the estimate and actual numbers in the forums.
I have yet to see an official Google response yet.
Forum discussion at WebmasterWorld and Google AdSense Help.