The kangaroo apple, Solanum laciniatum is abundant around Melbourne. I've got a luxuriant example growing in my garden (I'll get pictures). The fruit are irresistible to the feral blackbirds, so seedlings are appearing all over the neighbourhood. That suits me: the plant is from local stock and it's about time the natives took the place back from the roses and bloody agapanthus.
The blackbirds spreading the seed were introduced from Britain, which is almost (but not quite) ironic. The Natural History Museum in London has reported that kangaroo apple is now expanding its range in Britain. Botanist Joseph Banks brought the first specimens back to the UK in 1772 but the species seems to have remained under control until recently. Milder winter weather may be the key to its success. Whereas earlier escapees might have been nipped in the bud (literally) by severe frosts, these ones have managed to survive thanks to warmer weather.