The park is still there and operating, but not in its original form.
It closed about 12 years ago and remained closed for quite a few years but has now been reopened but with all new equipment. New slides and a very good walkthrough maze. Its a free park and if your every over that way its well worth the trip the kids would love it.
I could understand why it shut down as the equipment was quite old and the tall slides when you were at the top they used to sway from side to side quite a lot. No saftey bars or anything. Up the back there use to be a little coaster that you push up a ramp with a bar then jumped in and then look out if anone was in the road when the car went down as anyone the the way of the bar that u pushed the car up with it would of taken you out. Many of time i came away from that ride with grease and some very close calls.
Link to wiki website:-
http://en.wikipedia.org/wiki/Monash,_South_Australia
Here is sort of the best pic i can find of the new Monash park