A few days ago, JenSense had put up an entry about how some third-party javascript tools could very well mess up with AdSense, and make your site unvoluntarily go against their terms of service:
A warning to all AdSense publishers. It makes good business sense to dump all your cookies and take a spin around your website and see if any AdSense ad units pop up where you did not place any.
WebmasterWorld member morpheus83 happened to notice some strange behavior on his website – a mysterious 336×280 AdSense ad unit showed up on his site. An ad unit he didn’t place, and one that reveals a different publisher ID than his own. But on subsequent page views, that AdSense ad unit was nowhere to be seen. But lo and behold, it eventually showed up again.
A little digging around found the culprit – a third party javascript placed on the site to “tell a friend” about the site. These javascripts are popular with webmasters, and in 2003 this website already had 2,000 members signed up and using the service. Members recently received an email asking them to switch to a new code.
The update on this is that one’s account can indeed be suspended for such a trick. So, AdSense users, beware.