Unfortunately tried and failed by acclimatisation societies back in the day. They were one of something akin to 21 species/ subspecies of deer imported but there just wasnt the feed for them at the time. If you look at the invasive flowering plants we now have thriving in our urban centres - a trip on Sydney's north shore train line is an weed ecologists nightmare - a release of Muntjac or Roe could probably now be sustained by garden escapees on the urban fringe.

Tigers in NE Victorian high country would be fun, but I fear the poor buggers would starve without being able to chomp through mountain cattle as the biomass just isn't there. The smaller Vietnamese tiger might have a chance.

There has been a lot of work done calculating just what is likely to survive in Australia and what it would cost http://www.pestsmart.org.au/wp-content/uploads/2010/03/Risk_Assess_Models_2008_FINAL.pdf If you can find them Bomford's bioclimatic maps of where exotic animals could survive in Australia is worth a look.

In the meantime this is an interesting image to start people thinking "what if"

http://www.dailymail.co.uk/news/article-...-Australia.html