The claim has been made that the steel cores of the Twin Towers of the World Trade Center "turned to dust" on 9/11, and that indicates that some high-tech weapon (as opposed to explosives or something like nano-thermate) were used.
However, this video and this video show that the "spires" or remains of the core columns did not turn to dust. Instead, they collapsed into dust clouds caused, apparently, by the pulverization or crushing of tons of concrete when the buildings were destroyed. Note: to view the second clip you will need the free 3ivx codec which you can download here.
While there is, indeed, dust in front of the spires which obscures their views and the spires fall into a cloud of dust, the spires themselves do not appear to me to turn to dust. As someone else pointed out, the spire itself may even -- when it collapses -- throw off dust which it had previously accumulated when the towers collapsed around it. But that is a far cry from the spire itself "turning to dust". Use your finger to trace the movement of the spires and you will see what I mean.