ObjectPolicy is programming from XML. Objects from XML are mapped to objects in project and you issue commands against them. Command are issued from XML so you can store it into file or database, read and execute them. In that way you can program in run-time without a need to build your projects. ObjectPolicy has emerged from idea that user rights could be stored in database without hard-coding what happens when those rights are executed. With ObjectPolicy you have the flexibility to change and add new rights without changing the code of a project, building it and publishing it. That is just one of the examples what you can do with ObjectPolicy.
Addendum: ObjectPolicy reads, interprets and executes commands written in xml, it's not standalone solution, you need to implement it in your application. It's all about mapping objects in xml with objects in your application, and issuing command against them, that's what ObjectPolicy does.
(VS 2010, c#)