According to the Australian Constitution, the next federal election must happen by April 16, 2011. That said, the PM has stated that we'll be heading to the polls some time this year. It may sound obvious, but if you want to use your vote to fight the filter, you should make sure you're enrolled and your contact details are correct on the electoral roll.
The deadline for enrolling to vote for the first time is 8pm the day the election writs are issued, which generally occurs between one and four days after the election has been called. If you've moved and need to update your address to vote in the correct electorate, you have up until 8pm three days after the writs are issued.
Enrolling is a painless process. But if you really want to make your voice heard, it is the first and easiest step in trying to initiate change. Not to mention the fact that if this year's election is even 1% as exciting as that GetUp! trailer, we're in for an exciting couple of months.