The stores concerned are located in George Street, Sydney; Bourke Street, Melbourne; and Queen Street, Brisbane.
Apple previously announced that all of its Australian stores will open at 8am this Friday. Only the Sydney CBD Apple Store usually opens that early.
Apple is encouraging potential customers to make 'personal shopping' appointments for Friday "to come right to the front of the line" even though "Booking an appointment does not guarantee we'll have your preferred model in stock, but we will certainly try to accommodate you."
Features of the iPhone 3G S include improved performance ("up to 2x faster" crows Apple), a camera capable of 3MP stills plus video, voice control, and a digital compass.
On Monday, Apple claimed sales of more than one million iPhone 3G S handsets, just three days after the new model went on sale in the US.
There had also been more than six million downloads of the iPhone 3.0 software, which adds features including cut and paste to older iPhones.
In one of his first public statements since taking a medical leave of absence, Apple CEO Steve Jobs observed "Customers are voting and the iPhone is winning.
"With over 50,000 applications available from Apple's revolutionary App Store, iPhone momentum is stronger than ever," he added.
Various reports claim Jobs has returned to work, but Apple has not issued a statement on the matter. Purported eyewitnesses have said he has been seen on the Apple campus at Cupertino, but that's not the same as a return to work.
Last week, the Wall Street Journal reported that Jobs had received a liver transplant earlier this year.
That's a far cry from the "relatively simple and straightforward" remedy that Jobs alluded to in his January 5 open letter, but is consistent with his January 14 statement that "my health-related issues are more complex than I originally thought."
Read more on Jobs' health, the iPhone 3G S, and Optus's stunt on page 2.
Amid claims from various commentators that Apple is in breach of regulatory requirements by failing to adequately disclose the state of Jobs' health, the company has not varied its previous advice that Jobs would return to work by the end of June.
Getting back to the iPhone itself, is it "3G S" or "3GS"? Apple doesn't seem to be able to make up its mind, with both forms appearing in company documents.
The GS suffix has a history at Apple, having been used previously on the Apple IIGS. Launched in 1986 (two years after the first Macintosh), the IIGS was the final member of the Apple II family and was withdrawn in 1992.
And is Optus's midnight opening a big deal or just a way of gaining extra publicity? Probably the latter (and if you want to claim that iTWire has fallen for the ruse, that's a fair point).
But ask yourself this: for which other handsets would an Australian carrier even consider a midnight opening?
"Customers are voting and the iPhone is winning" in more ways than one.