Well, we're currently waiting on the Battle Frontier season to start, but they haven't mentioned when it will start. Usually it shows on Toasted TV on Channel 10 in the mornings before it starts on Cartoon Network, though.
This is a really good site: http://members.optusnet.com.au/veemon/index.html
As soon as it's revealed that Pokemon will start airing, they'll post it up in the news if you want to keep checking. Otherwise just keep watching CN and I'm sure they'll advertise it before they start.