I can go back into my folder of PR statements to see, but I'm fairly sure that Microsoft has done precisely this before -- citing specific third-party software revenue or just software revenue. Sure, it's not hardware units, but it is something.
Edit: I should say, I think Sony has done the same as well. It isn't just one company, so I'm not picking on Microsoft specifically. I just happen to think that MS has released more useful info in their PR than the other two, so they came to mind more readily.