Preferential voting gives you more parties, but it doesn't make voters any more intelligent. The informed will have the option to cast their votes strategically knowing that the major parties look at the first round results very carefully to figure out what issues are important to people. The less than informed masses, however, will still just vote for who ever promises lower taxes and more benefits. As such, while we have a lot of parties out there, some of them pretty good (Looking at you Sex Party! *Wink*) you can still expect who ever panders to the lowest common denominator to get larger. Even the Greens have their shitty policy that exists only for uninformed hippies who would ban oxygen dihydrate.
The other really interesting aspect of Australian voting is that it is mandatory. Voter apathy is much less of an issue. While you can still make a void vote that doesn't count, you have to show up in order to make it, thus most will just vote anyway. While in a non-mandatory system politicians try to rile voters up into voting for them by becoming more and more extreme on various issues, appealing to a zealous few, in a mandatory system politicians shift towards the center in order to try and grab more voters from the other guy, appealing to a middle ground. As such, our right wing party is significantly less crazy than in the US... Still don't have gay marriage though, because the left wing is scared to piss off Catholics.
Finally, in case anybody was wondering about the significance of electorates, the simple version is we don't get to vote for our leader. I don't get to vote for Kevin Rudd or Tony Abbott. Instead, there is a mini-election in each electorate, in my case between Mike Kelly for Labor, Peter Hendly for Liberals and a few others. So everybody elects a member of parliament for their own little slice of the nation, and then that forms your parliament. The leader of the party with the most winners gets to be PM.
In reality it is more complex, there are actually two separate houses, senate and reps, and also there is a governor general who exists to fuck shit up for people, but you get the idea.