Excellent question, and one I asked Sony earlier today. Unfortunately, it has yet to get back to me. What I can say is the announcement of a 80GB unit gives credence to earlier rumours that a new PS3 SKU is on its way to Australia. Not that storage is an exciting commodity, with the average cost per GB of a 500GB HDD coming in at 20c.
There's also the strong possibility the 80GB will replace the 40GB. If the 80GB comes in at the same price as the 40GB in the US, and the 40GB isn't replaced locally or given a price cut... well, I'd be more than a bit upset with Sony, given the massive difference in US/AU RRPs already.
Update: Looks like Sony was too busy talking to Gamespot. It has confirmation the 80GB is coming to Australia, though there are no details on pricing. Thanks Luke P.