I used one of these (ZTE MF668) for about 3 weeks while waiting for my ADSL to be connected, a year or so ago.

I used Sakis3g (http://www.sakis3g.org/), and it worked fine from the CLI on my Ubuntu HTPC.

My only gripe with these devices is that if you don't use them every 6 months, Telstra will 'disable' the SIM card.

It will connect, and let you view the telstra website, but you can't put any more credit on it.  You need to then go into a Telstra store, and buy a new SIM card for it.

And then you get the next issue that Telstra won't let you buy a sim card, and put credit on it in one transaction.

You must buy it, activate it, wait 2 hours, and THEN put credit on it.

Bunch of ridiculousness.

     / Brett