I honestly don’t know.
If Labor holds on, it will because the electorate have decided to give Julia Gillard a chance - she’s only been Prime Minister for less than two months and some people will hesitate to throw her out before she’s had a chance. I’m a dyed in the wool conservative and I certainly won’t vote for her party - but even I feel a bit that way about it, to be honest. I believe a Prime Minister should have a chance to show us what they can do.
That may wind up being a major factor here.
Sadly I think Labor will win and worse yet, the Greens will have the balance of power in the senate (and worse yet, perhaps in the House of Reps as well).
Living in Canberra, I can tell you that having a Labor/Greens government is utter misery.