Thought I would post up a bit on this topic.
It is stuff designed more for a floor covering in commercial nurseries than anything else.
It won't stop weeds growing. weeds germinate in nooks and crannies on the surface, blown in by the wind.
When you put mulch on top of weed mat, that is what the weeds will grow in.
Found this tonight also
http://www.gregsindigenouslandscapes.com.au/WeedMat.htm