We just got our 100% usage email last night. On logging into the Telstra usage meter we've found that none of the downloads from the recent Steam sales have been unmetered. I'm quite positive the data came from the Telstra Steam Content Server as for one the games came down at 1.7MB/s (about what our 15mbit connection can muster) and two when you click play, you see a little banner that says content delivered by: Telstra Unmetered.
Has anyone else noticed this? I'm going to give them a call today, but I expect they'll just say there are no guarantees that you will connect to the Telstra server and we'll be forced to pay the overage.