NBN Co has confirmed that they will be offering its services to ISPs for free in the initial stages of the rollout to finetune the network's performance. According to Lucy Battersby at the SMH, Telstra, Internode, Optus and iiNet have all confirmed that they won't charge customers who are part of the trial during the initial stages either.
The catch, though, is that they also won't waive the fees customers are already paying for their ADSL connections. So it won't be free superfast broadband, it will be superfast broadband for the same cost as your ADSL connection.
It still makes me wish I were part of the initial trial...