Bush actually sent a lot of aid to the region, which has helped in relieving some of the agony of being an Internally Displaced Person (and appreciation runs high--UN reports a strangely high number of babies being named George W. Bush among Darfurian refugee camps), but the AU/UN security efforts have been largely ineffective at stopping the violence. And why? Some of it is a lack of resources (money, manpower, etc), sure, and that's what most people are complaining about. But the real problem is a lack of spine, frankly. AU and UN troops are operating under a very tight Rules of Engagement (RoE), and largely cannot deal with most problems they face, and certainly is not going to deter the Janjaweed or the Sudanese government from acting. The Government of Sudan is willing (currently) to drink what trade embargoes and UN Sanctions are on its shoulders in order to finish dealing with its Darfur problem (which is mostly that Darfurians are rebelling over socioeconomic mistreatment, and/or want their own country, and Sudan needs the land for oil, and does not want to be caught paying someone to stop giving them a hard time).
But very recently, some progress has been made. First, the Justice and Equality Movement (JEM, one of Darfur's main rebel groups) is in peace negotiations with Sudan in Qatar, asking for (frankly) not much. Khalil Ibrahim, JEM's leader, said "We are fighting for pure water supply, education, primary health care, electricity, food, job opportunities and participation in taking decisions." There are ways for the Sudanese to accommodate these wishes, but they will likely require electoral reform and cooperation with outside mediators (mostly to enforce promises, particularly demobilization).
Second, the International Criminal Court (ICC) has added Sudanese President Omar al-Bashir to a growing list of big-wigs in Sudan that have a warrant for their arrest for War Crimes in Darfur. This is the first time the ICC has issued a warrant for a head of state--quite a bold move. He is highly unlikely to be caught, but he may be feeling the pressure a bit--the Western world is continuing to step up its actions against Sudan's government for the Darfur catastrophe. And, if Bashir should travel to any of the ICC's member states, he'll be arrested and brought to The Hague. The warrant also more explicitly indicts the entire state as a genocidal pariah, rather than a bureaucracy of incompetence that was unable to deal with the Janjaweed. It is going to stop the fighting? Not today. But it's likely to give the JEM (who are not the rosiest of rebels, to be fair) some added bargaining power in Qatar.
But even if the external forces, the electoral reform, and the peace deal can be mustered, the Janjaweed has to be rounded up and demobilized. That's going to be tough, to say it lightly.