ANU is consistently ranked among the top two all-around unis in Australia, in no small part because of its research (being in Australia's capitol surely helps). Their med school is fairly new though, first class commenced c. 2005. Canberra was also recently ranked #1 among int'l cities by some int'l group for 'liveability' -- things like 'health status', 'education', 'cost of living', etc. It's also known as the bicycling city. However most people I know consider it a rather boring and ugly city.
ACT makes int'ls P1 (if they don't apply out-of-state, as monsterink says) because ANU most wants to keep their int'l student market, and because ANU is the only med school in ACT (and thus can more easily reflect its interest in ACT's Ballot).