While Tom Tom only releases updated POI (place of interest) overlays for Australia once a year, the Ozpoi website offers user-created data overlays which are more frequently updated, and can be hacked for use with other GPS devices including Navman, Garmin, and Mitac Mio.
Overlays include "safety cameras" (red light and speed cameras) and school zones. Check the site's update history to see what overlays are available and how recently they've been updated.
The site includes instructions on how to install the POI files on your Tom Tom, and how to convert them for other GPS systems using the free POIEdit software.
[via The Age]