I got an inch-long nail through a M+ tyre once, so yes they're p#######-resistant, not proof.
Speaking of which: one of my local cycling forums***, there were reports this weekend of numerous nails scattered along Yarra Boulevard, in Yarra Bend Park, a very popular cycling road in the inner northeastern suburbs of Melbourne. Unfortunately it's also part of my usual commuting route home, so I think for the next few weeks I'll detour around it

. I'll also be ringing the nearest Police station in that area later this morning, just in case nobody else has, because this kind of behaviiour has to be seriously discouraged!
***
on which I haven't posted in ages, and only read now, due to finding CycleChat far more friendly 
.