By the time this is posted Yasi will have hit Australia. There will be massive damage, and probably loss of life. Most New Zealanders will have friends or family in Australia, perhaps in the areas affected. I’m sure our thoughts are with our cousins over the ditch. This is the second hammering Australia has had in as many weeks.
Extreme weather events are becoming more frequent. “Once in a hundred years” or “once in a generation” events seem to come again too soon. In Northern hemisphere summers we are seeing deaths from unprecedented heat waves. In the Winters we are seeing massive snow storms (warmer air carries more water), like those recently in England and Europe, and currently gripping America.
An increased frequency of extreme weather events is predicted (with 90% confidence) by the IPCC. Do the facts fit the predictions? Yes. The resources at Wikipedia are a good place to start. In particular this brief paper points out that we would expect an increase in reported events simply because of increasing population and improved communications. But the author controls for this by comparing the incidence of earthquakes (not affected by climate change, but increasing) with the incidence of cyclones and floods (affected by climate change and increasing much much quicker).
I see no reason to doubt that extreme weather events will continue to increase in frequency and severity. Make what preparations you can. The experience of the Christchurch earthquake has left me personally in no doubt at all, that whatever it is, it can happen here.