Australian Prime Minister Julia Gillard is set to reveal the details of a carbon tax designed to help fight climate change and billed as one of the nation's biggest economic reforms for decades. Labor leader Gillard plans to tax Australia's top 500 polluters for their carbon dioxide emissions as a means of reducing pollution, changing energy use and building investment in clean sources of energy. Australian Prime Minister Julia Gillard "No longer will the nation's biggest polluters be able to pollute our atmosphere for free," Gillard told a Labor Party conference on Saturday. "From July 1 next year, the freedom...