There's not a good standard way of doing this today. The closest thing you can do is model the OS as a "SoftwareInventory" instance underneath the UpdateService, but this becomes problematic in that it's hard to associate the instance with a system, and also know that this is an OS image. I'm not aware of anyone doing this today though.
However, that being said, we are looking at methods for showing this type of information on a system in an interoperable manner. We'd welcome any soft of feedback in this area for any preferences in how it's modeled.