I'm off to the beach (Apollo Bay) next week and decided I needed to remain connected to the net. After checking around I found that Telstra is the only carrier that has coverage down there. Further checks implied that their USB broadband modems worked under Linux. After checking out the option I bought Telstra's casual plan and their "Telstra Turbo" USB mobile. This has the advantage of being able to be discontinued between uses. The price per GB is about 5 times greater than other Australian carriers. On the other hand, Telstra really do have a very wide coverage and this really is expensive. The other carriers are essentially limited to just metropolitan areas.
I spent an hour or so futzing around with settings, searching the internet etc until I eventually discovered the SIM card was not properly inserted! Hint make sure the lights show blue not flashing orange :-)
After getting it properly seated I just clicked on network manager, chose mobile broadband, chose Australia, Telstra, default settings, clicked OK, requested a connection to Telstra and hey presto it worked!
Yay! This is exactly the experience I want :-)
Congratulations to Fedora 12 and the network manager team.