The good news? Telstra has, as anticipated, announced that its Next G network has been upgraded and is now capable of speeds up to 21Mbps. The bad news? It's neither as fast or as available as you think. To quote the press release:
At launch, the 21Mbps rated modems will be available to some business customers, with a consumer offering available in April. Customers with these devices will see typical download speeds ranging up to 8Mbps.
In short: it's not quite as fast as it sounds, and it's not available yet. But Lifehacker will certainly be testing it when it is.