The managed wrappers make it possible to utilize the new v4 runtime activation APIs from managed code. These APIs allow you to enumerate installed runtimes, probe processes for loaded runtimes, inspect runtime information, and use runtime activation policy. This would allow a managed application to provide an in-proc SxS-aware extensibility model, or merely react to its environment in an in-proc SxS safe way.
The wrappers are made up of 2 pieces. First, a set of interop definitions packaged as a Primary Interop Assembly (PIA) for the new shim APIs. These give you low-level, direct access to the shim APIs from managed code. These can be utilized in your code using the "Type Embedding"
feature, which will be the default when adding it as a reference in Visual Studio.
Second, a set of managed APIs that wrap this functionality in a more “managed API” way. These consume the PIA in the same way that 3rd party code could, but expose functionality using standard managed code concepts like properties, strings, and IEnumerables rather than their native COM counterparts.