One of the facts of business life today for many sectors is that you're forced to work with your competitor on one deal and compete against them in another -- coopitition. IT organizations need to have a plan in this space, to support their corporation business model.
The same situation is true in politics, both at the local and global level. In this situation, the use of information can be key to allowing the relationship to exist. Being able to share what's important for one situation and retract that access once the situation/relationship has ended, allows the data owner to have greater confidence that their being protected.
This article from some folks at HP is one view on addressing this situation - although it is more focused on the retail consumer information space. The consumer space is ripe for legal protection, requiring the use of privacy enhancing technologies.