According to the Google AdSense Blog, “Expandable ads will be served as third-party ads and will be created by Google-certified rich media vendors for the top display advertisers in our network. And like other Google ads, you’ll earn based on whether the expandable ads on your site are priced on a cost-per-click (CPC) or cost-per-impression (CPM) basis”

And, here’s the cool part, “You’re automatically eligible to receive expandable ads if you’ve added the AdSense code directly into your site’s source code and you’ve enabled image ads.” So no changing AdSense codes to get the Expandable ads? Sweet!

You can read the entire blog post here.