I'm 25, and I've lived in Australia my whole life.
Last year my (23-year-old, 6'7") LittleBro was a 'Santa's Helper' at Myer (big department store) and the 'Santa' outfit he wore was red jeans and a long-sleeved red cotton top, but the traditional pattern with the white fluffy trimming and black buttons.
It was funny, really, a lot of kids questioned him on why his beard was so short and brown, but he kept calling himself Santa Jr. and the kids thought it was awesome that Santa's son was chatting with them while his Dad was making all the presents up at the North Pole. He even wore the hat.
We also get Santa visiting us first, you know. Check NORAD. Seriously, he comes by Australia, Perth first, then across the Nullarbor.
A lot of Australian depictions of Santa are of him chilling on the beach, he gets about a half hour respite between us and NZ, he's that quick, so he usually has a beer in Bondi and then the police make sure he's not over the limit before they send him on his way.
I do think that we perpetuate the myth a little more tongue-in-cheek than most countries, most kids accept as early as three or four years old that the "Santa" in the shopping centre isn't the real deal, he's one of Santa's Helpers who is sending their wishes back to the Big Man up north. A lot of Australian houses lack a fireplace, too, so he can't really come down the chimney, so we have to leave a door 'unlocked' for him to get into the house, or remind kids that he is magic, and can get in no matter what.
Either that or he uses the AC vents.
The guy in the red suit still uses the sleigh, but most people in this part of the world honestly have never seen one (I don't know anyone, outside people who've been to the States or the UK in winter) who has actually seen a sleigh, let alone has a complex knowledge of how they run - plus, it is a magic sleigh, so snow isn't exactly a requirement for it to run.
I have to concur with Cellach, I'd love a white Christmas, and almost got one a couple of years ago - I was at Cradle Mountain in Tasmania and on Boxing day we got 2" of snow... it was 43 degrees in Darwin, high 30s in Melbourne, mid 30's in Launceston (just 200kms away) and it snowed, enough to hit Ace with a snowball, up on that mountain.