Edit Oct 2009: Since I originally wrote this article, SkippySky has become available. It uses the same US GFS weather model data so the discussion about accuracy is still relevant, but SkippySky is a much more convenient way to access the cloud forecast data, with great maps for all of Australia among other places.
Check out Cloud Forecasts for Astronomers for the story behind some of this and how to generate your own cloud forecast maps using US GFS model data.
Also see Cloud Forecast Accuracy for comparisons of the forecast charts with actual satellite images.
Heathcote, Central Victoria
Jeff Bullard has a simpler forecast which shows just night time cloud forecasts for a given location, but is based on the same GFS data. Here is the live Astroforecast for Heathcote, Victoria:
Australia MM5 Model Charts (Air Force Weather)
AEST is 10 hours ahead of Time shown at top right of image. Click the image to load the interactive animation loop and then you can choose an image for a different forecast time.
Colours indicate cloud top height (thousands of feet). No colour equals clear-ish sky.