Myxoma virus has started to be pretty ineffective and in recent years the CSIRO came up with the calici virus. For a short time after its release (unintentionally premature I believe) it really hit the bunnies hard. However, it will only be a matter of time before the rabbits develop resistance to that. The battle with the rabbit continues.
Other brilliant introductions to Australia include the fox (again for english gentry to hunt) and the cane toad. That was some genius in the sugar industry who thought they would help eradicate some pest in the cane fields. They did not! and now they are spreading across the north of this country with no predators to slow them.