Simon has linked to a couple of papers on materiality in social research that he has written [in partnership with Simon Blyth of Unilever] that are well worth reading. Most stuff around Actor Network Theory [ANT] doesn’t seem that helpful to the average researcher doing research, in fact most Social Science ‘theory’ seems elitist and irrelevant to me. But whilst ANT and particularly Bruno Latour’s work is [in my opinion] probably the best thing to happen to Social Science in the last fifty years it hasn’t made a huge impact in terms of telling stories about the world to inform better design. Simon’s papers’ are of the few I’ve seen that try to make materiality matter to a wider audience. Why?
Well, I think we tend to anthropomorphisise materiality and / or consign non-human things to the status of second class citizens. This is mostly as a result of the belief in ‘agency’ residing only with ‘us’ when actually the ability to have effects resides in everything, but only as a result of a coming together with other ‘things’, what ANT is all about; networks of association. And being drilled in a humanist reading of life that’s hard to take. We like to think of ourselves as special 
That said many of the people writing around design and experience design in particular seem to be influenced by "materiality". Terms like ‘affordance’ seem to spring up in conversations I have with people in design, so there seems to be a tacit acknowledgement that it’s important. But in terms of doing the background to inform design it’s tough to know where to start. My old superviser once said to me – when I was struggling to get to grips with how to research materiality – that ANT was basically about being as granular in ethnographic work as possible and not taking anything as a given. That helped.