Australia has a new Prime Minister after an internal coup d'etat by the ruling Labor Party replaced Kevin Rudd with Julia Gillard. They ditch leaders quite a lot in that party, Rudd himself came to office when he knifed Kim Beazley. Several other Labor leaders have found themselves unceremoniously dumped starting with Bill Hayden 30 years ago who was replaced by the much more effective Bob Hawke.
The ruthlessness of the party is in stark contrast to their British equivalent, our Labour Party develops a sentimental attachment to their leaders no matter how useless they turn out to be and no matter how much it hurts their party. Michael Foot, Neil Kinnock and Gordon Brown have all benefited from this. The only leader they have knifed was the one who brought them multiple election victories.
The Australians have it right in my view, keeping a leader who isn't cutting the mustard is a betrayal of the voters, especially in a two party system.