<i>App Engine for Business allows you to use SSL (Secure Sockets Layer) on your own domain for all your App Engine applications, not just on the x.appspot.com domain.</i><p>FINALLY!
This certainly doesn't seem like AppEngine for small businesses - $8 per user (capped at $1k) per month seems like a heck of a lot if your service doesn't require much in the way of processor/storage.
<i>"SQL database support on App Engine gives enterprise developers access to the full capabilities of a dedicated relational database, without the headache of managing it."</i><p>Wonder which RDBMS they will offer, MySQL?