In this video, Nokia’s developer channel shows some examples of in app purchasing. You can see that the payment is tied to the Nokia account and paying through the phone bill. Here the purchases allow for additional levels download or more items to be unlocked. As long as we need to keep entering the account password each time, that’s fine. I can imagine racking up a huge bill if that wasn’t the case (or if this ended up in a child’s hands).
This video highlights two demo apps, QuickHit and Moto Trial Racer. These introduce non-DRM and DRM implementations of In-app Purchasing in Qt apps.