Since 1st of July, my adsense earning has a big decrease … too bad, it is about 50% :(. My site is having the about the same stats with previous month: unique visitors, page load, ads impression, clicks … all are about the same. Only the average cost per click of adsense ads has dropped about 50%.
Webmasters at webmasterworld.com disccussed about this topic too . Some of them think the phenomena is caused by the HOLIDAYs in USA (hmm … most of my visitors are from USA and Europe). Hopefully it will back to normal as soon as posible.