Grant has done some work to make new imagery available for Australia. It’s grayscale imagery for all of Australia at 2.5 metre resolution.
Read more about this on the talk-au mailing list, and load the imagery into your editor as follows:
JOSM tms url: tms:http://agri.openstreetmap.org/{zoom}/{x}/{y}.png (or just pick it from the ‘available default entries’)
Potlatch background url (Background > Edit> Add): http://agri.openstreetmap.org/$z/$x/$y.png (It will be added to Potlatch imagery default in a few days.)