First I should point out that possums in Australia are absolutely no relation to the possum or opossum in USA. Unfortunately when this continent was first explored by white fellers the botanists in the expeditions were often pretty unimaginative men who named newly discovered plants and animals after similar looking ones they knew back home. So now many generations later we have a legacy of ash, box and oak trees, magpies, and possums, even rats, that are no relation to the animals with the same name on the other side of the planet. Many of them actually bear little resemblance.
Also: All native wildlife is protected and can't be hunted, killed, kept as a pet or sold.
Possums are protected but are quite common, to the point of being a pest in some areas including some cities.
(A bit of background info so you might get the joke which follows...)
This thread reminds me of the tale of the man who was out camping in the Australian bush. He had a campfire going and had just cooked himself a meal of possum. He had eaten about half the possum when he was apprehended by two wildlife service rangers who arrested him for killing and eating a protected native species. He was kept overnight in the police lockup and was in court the next day.
The Magistrate told him he was charged with killing and eating a protected species. This was a serious charge and he was in a lot of trouble. The magistrate asked, "How do you plead?"
The camper admitted he did eat the possum, but pleaded not guilty anyway because he was lost in the bush and was starving, only killing the possum to save himself from starvation.
The magistrate decided that this was a sufficient reason and dismissed the charges. Before releasing the camper, the magistrate asked him, "tell me, I have long been curious. What does possum taste like?"
The camper replied, "well, a bit like platypus and a bit like koala."
Chris.