Assuming Kevin Rudd forces are right and the ALP leadership question comes to a head before the end of the 43rd paliament, the incoming prime minister would need to presumably swear in a new cabinet before an imminent election. The best parallel would be the Malcolm Fraser caretaker cabinet sworn in on November 11, 1975, comprising 15 members. Or Rudd could "do a Whitlam" and appoint himself and a modern-day Lance Barnard (probably Bill Shorten) to all the ministries. Or he could reprise his famous four-member "kitchen cabinet" in a formal capacity for the 11 weeks before polling today.
A clean-out of the Prime Minister’s Office would also occur, with Rudd media adviser Patrick Gorman presumably taking Ben Hubbard's gig as chief-of-staff and communications tsar John McTernan making a beeline to Glasgow via Heathrow.