For the second time, a cease-fire has been reached between the Sudanese government and the major rebel militia groups in Darfur. The cease-fire involves a 60-day cessation of hostilities, leading up to a peace summit with the African Union, the UN, the Sudan, and rebel groups. However, no one should be holding his breath in anticipation that this cease-fire will work.
First of all, negotiations like this always create a collective action problem wherein any group not party to the deal has a strong incentive to defect from the deal. [Sometimes this even applies to a group party to a deal but with multiple decentralized factions, such as the ETA, which announced that despite conducting a bombing in Spain over the New Year weekend, its cease-fire deal with the Spanish government is still in effect. In essence, because Spain has more to lose by scuttling the cease-fire, the ETA has a "get out of jail free" card.] This is what brought down the first cease-fire deal, and unless each and every Darfuri rebel group is included and has an incentive to adhere to the deal, it will, very shortly, be violated.
Second, the Sudanese government has, shortly after annoucing the cease-fire, reconfirmed that it will not allow UN troops to join or replace the too-small and too-weak AU peacekeeping force already on the ground in Darfur.
Nex Mexico Governor Bill Richardson, currently in Darfur and involved in the cease-fire negotiations, stated that "we've achieved something significant. It needs to be followed up. But unless there is proper implementation and follow through, this agreement is still up in the air. But I believe we've made an important breakthrough."
Unfortunately, Governor Richardson's comments are very likely premature. Neither the US nor the UN has demonstrated sufficient spine to enforce any deals or agreements, and has hardly mustered the energy to put any real pressure on Sudan or its protector, China. Until that happens, the situation is unlikely to improve.