And as if that wasn't enough, now with no plans? you can call Vodafone to Vodafone within Australia for 20c. That's just 20c for the whole call (generous call caps apply, excludes roaming). So you can talk and talk and talk!
And that does not seem to have any limitation on the time of the day when the call is made (aka Optus' week night/weekend bonus). I am not exactly sure when this "promotion" started, but definitely sounds a good deal to me.
All I need to do now is to find some friends on Vodafone.