The free deal applies to both prepaid and postpaid customers. You can also update your own status via text, though that will be charged at the applicable rate (which could be anywhere from nothing to around 30 cents, depending on your plan).
Of course, in an era where increasing numbers of people have smart phones with dedicated Facebook clients, this might not seem like much of a feature. Nonetheless, there are still lots of people who only use more basic phones, and even data addicts find SMS useful when connectivity is a bit questionable. I’d still rather have free Twitter updates via SMS, but it’s a start.
To activate the service, Telstra customers need to text ‘fb’ to 019832665, which will send you a confirmation code in reply. You can tweak the frequency of updates to only include certain types of updates, to not send SMS messages while you’re logged in, or to switch the service off (essential if you’re heading overseas where roaming charges might get nasty).