Nobody can be sure whether the deal reached in Sadr City will be any more successful than previous attempts at securing ceasefires in Shia radical strongholds.
By David Bamford
BBC security correspondent
It also remains to be seen whether this carrot-and-stick approach can succeed elsewhere, but this is what Iraq's interim government is hoping.
For the Shia militiamen in Sadr City, the stick involves the threat of continued US bombardment. The comprehensive military action against Samarra, and earlier fighting in Najaf, were intended as examples of US-led military resolve.
There are two carrots. One takes the form of substantial cash payments, the other the opportunity of political inclusion for the Shia militant leader, Moqtada Sadr.
His militiamen have agreed to hand in heavy and medium-sized weaponry - mortars, rocket-propelled grenades and munitions launchers - though they are to keep their Kalashnikov rifles and small arms.
In return for this, the militiamen are being paid for their weapons, and the Iraqi administration has apparently agreed to earmark $500m for the redevelopment of the Sadr City slum.
The amount of money involved may be the key element that makes this truce work, and the same may be attempted in the Sunni stronghold of Falluja, where an Iraqi defence ministry delegation has opened negotiations.