What I don't understand is why they aren't letting these sit side by side Adsense and Google.com ads. It wouldn't be hard to figure out a profit per display metric, although it would need one or two order of magnitudes more displays to calculate. Maybe it will once it's out of beta?

It surprises me that they didn't hook this up to Checkout first (http://news.ycombinator.com/comments?id=2087). It would have been much simpler for webmasters that already use Checkout to get started, and for Goolge to track.