Interaction design and subject-object relations

I've been getting back to reading sociology recently, and refreshing myself of on interaction design concepts at the same time. I need to be up on both just to finish the white paper i've been working on for so long... I had a thought this morning though while going through alan cooper's section on software posture. We designers use a conceptual framework that treats software applications (and devices too) as objects. As designers, we seek to improve these things, and their interface to us, so that they work better.
It hadnt really jumped out at me that my project to define a "social interaction design" field requires us to think in terms of practices rather than objects. Cooper's chapter on software posture now takes on a different meaning. In it he asks questions that characterize an application's boundaries—it's presence in our routines, its hold on our attention, its ability to do things for us in our absence, its persistence as an auxiliary app (e.g. windows taskbar).
In social software, and communication technologies in general, the object boundary is deceptive. And to think about design in terms of objects may be to misleading, too. Because the crux of interaction design w/ social software and communication technologies is in the user and social practices that develop with, around, and through the technology. The thing itself loses its edges, and thus its interface...
Think about it this way. Take your cell phone. Now dont look at its buttons, screen size, form factors. Just turn it off. Now you can start to think about its interface! How do you feel? What's missing? What's gnawing at you? Why do you want to turn it back on? ....

There's Heidegger hiding in here somewhere.