Tradle today allows sharing on a very granular level, per object. Patrick suggested a scheme where an owner of the data would get the data from a secure storage, decrypt it and then launch a virtual machine / Container to provide a function to access the data. Example he gave was a function would answer a question - are you near me right now without revealing the GPS data behind it.
This approach could be used when there is a large volume of objects and issuing permissions on per-object basis is not feasible or not privacy conscious. This applies to fitbit personal data, and to sensor data from power plants.