For those interested, the answer is:
// get a type by asking the remote server for it
Type type = Type.GetTypeFromProgId("Foo.Bar.Thing", "18.104.22.168");
// then instantiate it with the reflection activator
IFooBarThing thing = Activator.CreateInstance(type) as IFooBarThing;
Aparently, things just got moved around. The functionality is still there.