Google AdWords Pay-Per-Action is in beta and they’re answering your questions here. I’ll be watching closely how they plan to handle advertising accounts that get very low conversion. If you only pay-per-action, what happens when nobody takes an action? Was that free branding you just got?
Also in AdSense news, the AdSense API is ready for developers. Watch for smart marketers to develop products that help you manage and optimize your AdSense account. You might want to subscribe to Google’s AdSense Calendar for updates.