The ALP faces an existential crisis.
Rudd's resurrection is a desperate last throw of the dice for a party struggling for relevance in the second decade of the 21st century.
The last prime minister to make a successful comeback was Menzies in 1949, he went onto to be Australia's longest-serving national leader.
When Menzies lost office the first time in 1941, the venerable Alan Reid, perhaps the most important important Canberra Gallery journalist ever, wrote a column declaring that Menzies' career was over.
Not a few times in the 17 years Menzies spent as PM after defeating Chifley at the national election in 1949, he delighted in reminding Reid of that column.
Anything is possible.
Only two other prime ministers have made it back to office (Deakin and Fisher).
Unlike Menzies, Rudd did not return to office by way of a general election.
Rudd promises party reform, Menzies created the modern Liberal Party as the platform for his return to power.
In this sense, Rudd's return has been too easy, too quick.
I think he should have waited until after the election, just as I thought Gillard should have waited too.
Winning an election from Opposition confers a lot of legitimacy on Australian PMs, a legitimacy that can't be gained any other way.
Rudd's resurrection by way of a party room vote is a unique event in Australian politics.
The fact that the federal ALP has now lost its last two leaders through party room coups is hardly a good look.
It suggests a party that is struggling to hold together.
Also extraordinary have been the retirements of senior caucus figures over the past few months, mostly prompted by leadership disputes one way or another - Chris Evans (Senate Leader), Nicola Roxon (Attorney-Genaral), Martin Ferguson (Resources), Simon Crean (former leader and Cabinet Minister), Greg Combet (Climate Change), Peter Garrett (school education), Craig Emerson (Trade), Stephen Smith (Defence) and Julia Gillard (PM).
This list included two former ACTU leaders and a former ACTU secretary.
As a reuslt of the Rudd resurrection, two of the Gillard governments most senior figures now sit on the back bench, not retiring but not serving in the Ministry either - Wayne Swan (Deputy PM and Treasurer) and Stephen Conroy (Senate Leader).
No matter what you think of the people on this list, it is difficult to imagine that this number of senior people can depart in such a short time without weakening the Government's front bench.
It is also difficult to believe that the party can just put behind it the trauma that it has endured and work together for the common good.
There is a lot that is personal in these struggles that will not easily go away.
Rudd asks for a 'kinder, gentler' approach, but much of the ALP believes that he was methodical and vicious in his efforts to undermine Gillard, Australia's first female politician.
Perhaps the more important question, however, is the extent to which a leader, or a change of leadership, makes to a party's electoral fortunes.
Gillard got a bounce when she took over from Rudd which was similar to the bounce Rudd got this week.
By election day several months later, Gillard's bounce had all but disappeared.
Maybe that was at least partially due to Rudd's (or his supporters) destructive leaking.
But in NSW at the last state election, Kristina Keneally took over from Nathan Rees and ran a much admired campaign as that state's first female premier.
Nevertheless, the ALP's election vote was not much different to the poll results that Nathan Rees was getting before he was dumped.
On the other hand, Bob Hawke was said to have added about 2 percentage points to the vote the ALP got in 1983.
It is also probably true, that Hawke would have been beaten by Hewson in 1993 - but who knows.
A second consideration is the real nature of the ALP's problems.
Is it leaderhip? Is it policy? Is it the brand?
Gillard came to office promising to fix the policy areas that had troubled her predecessor's administration; particularly the mining tax, asylum seekers and carbon pricing.
Rudd returns to office facing big challenges in these areas.
What can he really do, especially in the few weeks left until the campaign starts?
Plus, Rudd has to try and get a finalisation of Gillard's school reform project.
He has to do all this with not much room to move in budgetary terms.
The brand question has two dimensions.
First, there is the public perception of the party especially in NSW where the ICAC matters, and the HSU (and Craig Thomson) keep on hurting the party.
But it also goes to organisational problems - unions and factions - and the sense that the party is run by self-perpetuating elites.
How the ALP handles upcoming preselections for the aforementioned retirees will be important.
If the ALP leaders just impose candidates in a handful of safe electorates now left vacant the perception of a party without members and run by a few dozen union officials and MPs will be re-enforced.
Moreover there is brand Rudd, roundedly trashed by 'colleagues' during various episodes of leadership tension in recent years.
Rudd, and everyone else on the government 'team', now says he is a changed man. We'll see.
On the plus side for the Government, and perhaps their best hope, is the Opposition leader.
Abbott is unpopular, he did not handle Rudd very well last time, and he has so far been able to avoid much close scrutiny.
If Rudd and the ALP can minimise their own mistakes, and play down the festering tensions and resentments, and focus on Abbott's all too obvious flaws - well who knows what might happen.
But it's a long shot.
In the end, the most likely result is that the ALP will do slightly better under Rudd than it might have done under Gillard.
That won't be enough to stop the party from facing some very dark days over the next few years.