I did a quick search and the official broadcaster in Australia is the Seven Network but didn’t see any live streaming link on their website. It might be there but I think NBC would block any US access by computer like they have for the CBC online stream too.
I am not an expert on Australian media, but I am pretty sure the network I was listening to was the Australian Broadcasting Corporation (Company?) on Radio Australia and I think Australia has several networks. Anyway, it was a pleasant surprise to hear live coverage of the opening ceremony for an hour or so until the signal faded out. So I was hoping that those fast Internet connection could try the Australian ABC network and find something. Just a hunch. I think someone here said the BBC has live streaming coverage but has blocked it for U.S. viewers.