I can confirm that Emu Farming ended up, like Deer Farming (as Con suggests) with Emus being released, or simply escaping. For example, at Sassafras, (high on the southern end of the Illawarra range). There are some Emus "free ranging" there amongst the paddocks - surrounded by cool temperate rainforest. Hardly their natural habitat.
Anyone driving from Nerriga to Nowra, might see them in cleared farm lands around Sassafras. I have also seen some, further east and much lower down, on Turpentine Road, between the Nowra Rd and Princes Highway. But this last group were properly fenced in, as if they are being "farmed".
But I am fully confident that the birds Martin saw (and my friend photographed last year) are likely to be naturally occurring Emus. After all, there is still connectivity of habitat in the far south-east of NSW between the "high country" population and the south-east heathland populations.
Regards
Denis