Techcrunch has a copy of an email which The Google AdSense Team is sending out to Facebook Application Developers, trying to convince them to buy AdWords Pay-Per-Action ads. That's right, the *AdSense* team is sending out an email to sell *AdWords*. No wonder people get confused between the two...

<< Would you like to drive more users to your app? We’ve expanded our pay-per-action (PPA) beta test and would like to invite you to participate by creating ads for your Facebook application.
[...]
Sincerely,

The Google AdSense Team >>

From: http://www.techcrunch.com/2007/10/31/google-is-courting-facebook-developers-in-more-ways-than-one/

Via: http://google.blognewschannel.com/archives/2007/11/02/google-emailing-facebook-developers-to-use-adsense/