The Guardian also previews the speech with a news report, in which Miliband warns his party against complacency following its victory in the first by-election under his leadership.
The conference (full agenda) is sold out. If you can't be there, you can follow our debates and discuss the event on the twitter hashtag #fab11, and we will be tweeting from @thefabians, while I will be on @nextleft.
Here is an extract of Ed Miliband's Guardian piece:
We lost the general election last May, but David Cameron did not win it. Most people cast their votes for parties that talked about the need to make Britain fairer and more equal; that warned against the dangers of cutting the deficit too far and too fast; that promised to protect health and education; that called for a more responsible financial sector; and that urged a deepening of democratic reform.
It's easy to forget today, but the brief bout of Cleggmania last year was animated by this hunger for change. Even the Tories have sometimes sought to drape themselves in this mantle.
There is a progressive majority in Britain. The great Labour governments from 1945 to 1997 all won power because they became the voice for that progressive majority. Last May we failed because we were not that voice. As a result, we have a government of the neoliberal right with a reckless economic agenda.
Labour's response must be to understand where we lost our way and how we can rally all those who share our values in other parties and in none. To do that, we must be willing to change.
Citing the need to recognise the importance of liberty, Miliband cites the importance of liberal reformers like Beveridge and Keynes in Labour's own history, Ed Miliband welcomes LibDems who have moved to Labour but also writes that he respects those Liberal Democrats "who have decided to stay and fight for the soul of their party" and wants to "co-operate with them in parliament and outside it" with those "who have the courage of their convictions" and wish to challenge the direction of the government.
Saturday's Independent reports that Miliband will say:
"Forgive me if I decline to join those of you who are gloating at the expense of the Liberal Democrats. Their decision to join a Conservative-led Government was a tragic mistake, and I hope they come to see that in time."
Miliband will also talk about the need to reconnect with what he calls Labour's own "lost traditions of mutualism, localism and solidarity" - suggesting that limits to "free market fundamentalism" are needed to conserve the institutions and relationships people value.
An influential voice on the Labour leader on these themes is Maurice Glasman, recently appointed to the Lords as a Labour peer by Miliband. Glasman will speak on a conference panel, having contributed a new Fabian Review essay on the importance of Labour's traditions of community to the party's identity.
Miliband will pitch to what he calls the "real centre ground of British politics", according to extracts released by the Press Association, and reported by Bloomberg.
I want to become the voice and hope of those who feel squeezed by an economic system that promised to liberate them. I want us to articulate the frustration of people who are fed up with bankers taking vast public subsidies and then rewarding themselves for failure while the rest of the country struggles.
"I want us to be the party that answers the call for a fairer sharing of the nation's wealth, strong and responsive public services and a different kind of politics. This is the real centre ground of British politics and it is our duty to speak up for it."
Fabian research director Tim Horton wrote this week for The Guardian about the battle of middle Britain - and the "angry middle" concern at bankers getting a free ride, drawing on Fabian research for the Joseph Rowntree Foundation, and the Fabian/Webb Memorial Trust book The Solidarity Society.
More conference previews
Sunder Katwala on the electoral mountain for both major parties at the New Statesman.
Mehdi Hasan says Miliband must seize the moment.
Will Straw argues that Simon Hughes' progressive claims don't stack up.
Daniel Elton on the lessons from the right for movement politics.
The Fabian Review conference special editorial on Ed Miliband's 2011 challenge
Paul Richards for Progress on what an alternative might look like.
Also at Progress, Hopi Sen, Rupa Huq and Sam Townend advise Ed Miliband on what to say.
Jason Cowley in the Mirror on Ed's road ahead
Andrew Grice in The Independent on the pitch to the radical centre
Tribune on Ed Miliband's challenge to the banks and the government.
During Saturday, there will be reports and coverage from our media partners The Guardian, the New Statesman and Left Foot Forward, as well as here on Next Left, and on the Fabian website too. LabourList and Liberal Conspiracy are among other major left blogs planning to report on the event.
If you blog about the conference, do please leave a comment with the link. We plan to round up reactions on Sunday and Monday.