Elephant in Australia?

Yes!!!
Because in my opinion, it can be really good for pest (invasive plant species) control and fertilizing the land.

This is the story: http://www.smh.com.au/environment/conservation/expert-advises-big-fix-for-jumbosized-problem-20120202-1qtzb.html

Elephant in Australia will be for good. They will certainly eat grass and small plants but I doubt they'd eat the gum trees with too much oil. Researchers can feed them different types of plant species and just find out. This is about a grand plan - saving Australia or Australian rare species. There should be some funding for the research and quite simple enough to be done within a month. Just get a few elephants and give them variety of plants and grasses and just find out.

 They will pursue for easy food (grass) rather than forcing the trees down - unless very desirably tasty, or no easy meal found. Water might be a problem for them if water holes are rare and that could be a problem for the native animals too.

Generally elephants are peaceful herd (social) animals. They are smart and kind - except for the bulls when being threatened or during their musth.

Here in Australia, you can try an old mowing strategy - using goats or sheep. Now use elephants and employ some mahouts from India, Burma and Thailand. For the mission, either Asian elephants or African elephants or both will be fine.

Well, I'm not suggesting wild elephants to be released unattended by the experts. In this case, about a thousand elephants would be just fine. Just put the elephants in missions for pest control and they will look after themselves. Place them in different locations in several herds and everything would be fine...