Yes, you are if you lodge as a nonresident.
As a nonresident, from July of 2012, you are subject to tax on 32 1/2 cents or roughly a third of every dollar you earn. This goes up to $80,000.
In addition, you cannot take advantage of the tax-free threshold of $18,200. Australian residents pay no tax on the first year of their income up to $18,200, and you are not eligible for any of the tax offsets Australians benefit from.
However, unlike Australian residents, you do not pay the Medicare levy and are not subject to tax on any foreign income you may receive while in Australia.