Labor's Kevin Rudd Returns as Prime Minister of Australia

Julia Gillard to sacked. See the Guardian UK, "Julia Gillard ousted as Australia prime minister":

Australia's first female prime minister, Julia Gillard, has been sacked by her party just months before the next election and replaced by the man she ousted three years ago.

After an unprecedented day of political bloodletting in Canberra, Kevin Rudd beat Gillard in a ballot of MPs by a margin of 57 to 45 to become Labor party leader. It is only the second time a sitting Australian prime minister has been removed from their first term in office by their party; Rudd was the first.

Delivering his victory speech, Rudd dedicated himself to winning the election in September. "In 2007 the Australian people elected me to be their prime minister. That is a task that I resume today with humility, with honour and with an important sense of energy and purpose."

He also paid tribute to Julia Gillard. "She is a woman of extraordinary intelligence, great strength, great energy. All of you across the nation would recognise those formidable attributes," he said. "Julia has achieved much under the difficult circumstances of minority government, helped by a dedicated set of ministers."

"She has been a remarkable reformer and I acknowledge those contributions this evening," he said.

Rudd said he had taken on the challenge of the leadership because he could not "stand idly by and allow a (conservative) Abbott government come to power in this country by default".

There's background on Gillard's sacking at the link, although I like this:

Conservative opposition leader, Tony Abbott, whose party is well ahead in the polls, criticised the revolving door of Labor leadership, saying Australians deserved better.
"She has been a remarkable reformer and I acknowledge those contributions this evening," he said.
"In 2007 you voted for Kevin and got Julia," he said. "In 2010 you voted for Julia and got Kevin. If you vote for the Labor party in 2013 who knows who you will end up with."