cabincrew88 - i did my medicals in sydney but not at the qantas jetbase, the doctors are able to tell you on the spot if you pass or not cos they can pretty much see if you're physically fit, i asked them if i will find out and they said yes the doctor will let you know right away.
just make sure you have all documents and get all vaccinations done beforehand! cos that can take some time waiting if you havent done all those