Newspoll data is available back to 1993, but only becomes frequent on a two party preferred basis in 2003 — I fondly remember the excitement of it all. Anyhow, they make their data freely available on their web-site.
Looking at the full data set, you can see how uniquely badly the ALP is traveling in the polls – though I suppose there is only one change of Government, and Howard was popular to almost the end, so we don’t have really have many data points. Still, this looks nearly as serious as the Coalition/Howard death-spiral in 2007.
Setting aside the fact that we may have a terribly small sample – and so little ability to truly support such conjecture – it seems that the ALP might have already lost the next poll (due 2013, if they can last that long).