Yesterday we reported that AdSense impressions were double reporting. Well it turned out to be more than just a reporting error. Google was double or triple serving the same ads on the same site, which is not something they should have been doing. In any event, Google has announced they fixed the issue:
If you're displaying multiple ad units on your pages, you may have noticed that your pageviews were higher than normal for part of yesterday and today. Our engineers identified a bug which prevented ad units from detecting other units on the same page. As a result, our system logged a pageview for each ad unit that was loaded on a page, instead of a pageview for each page containing ads. In some cases, this also may have caused specific ads to appear in multiple ad units on the same page.Please be assured that ad unit impressions were still logged correctly and ads were still displayed on your pages, so you were properly credited for all earnings generated from your ads. We've resolved the issue, and although you won't see the pageview count in your reports retroactively changed, your pageview tracking is now back to normal.
But like I said, some ads were double or triple served on the same page.
Forum discussion at WebmasterWorld and Google AdSense Help.