Amit Agarwal reported that Google AdSense updated their program policies to specifically mention you cannot place AdSense ads within IFRAMES.
If you check out the WayBackMachine you will see the "Ad Behavior" policy was:
AdSense code may not be altered, nor may the standard behavior, targeting or delivery of ads be manipulated in any way that is not explicitly permitted by Google. For instance, clicking Google ads may not result in a new browser window being launched.
But now it reads:
AdSense code may not be altered, nor may the standard behavior, targeting or delivery of ads be manipulated in any way that is not explicitly permitted by Google. This includes but is not limited to the following: clicking Google ads may not result in a new browser window being launched, nor may Google ads be placed in an IFRAME.
The bolded portion is what Google added.
I am not sure how many publishers this may impact but the policy was not made explicit on this topic.
Forum discussion at WebmasterWorld.
