The response from Skip was obviously a 3.0 based on (first printing date of the 3.5 PHB was July 2003).dcollins said:Yes. (Of course all you have to do is fall a certain distance that overcomes DR anyway. Even easier to do in 3.5 since they generally reduced the numbers.)
Here's the response I got from the Sage on this issue a while back:
In 3.5 DR is pretty specifically defined as only applying to natural attacks and weapons.