United States Africa Command (AFRICOM) assumed full autonomy and operational work on October 1, 2008. The new command's purpose is to better coordinate military and civilian operations on the African continent. While this may seem as a bit of a formality, AFRICOM is a huge step forward.
Combatant Commands, military commands setup on geographical lines around the world, were formalized in 1986. Africa at that time was treated as an extra and divided between the European, Middle East, and Pacific commands. Little in the way of military operations were planned in Africa as the continent was left to the diplomatic State Department and covert operations of other groups.
The world has changed though since the end of the Cold War. The spread of Islamic militantism from the Middle East to the Islamic frontier, the collapse of formerly Soviet and American client states, and the return of tribal warfare up to the level of mass genocide have brought Africa back to the world's focus. Military and policy planners realized this and decided the best way to help is create a hybrid combatant command with both military and State Department components solely focused on Africa.
The primary goal of AFRICOM is to coordinate better with African military officials and government heads, improve African-centric plans like relief operations, and aid in the War on Terrorism.
There are some nay-sayers, though. Some African leaders are afraid AFRICOM because they see it as a plan to have American political colonization is Africa. Many in this category see Africa as still fighting against the colonial legacy of Europe and do not want to step back. Others oppose the command because of their opposition to the United States. Eritrea, Zimbabwe, and the Islamic Somali rebels fall into this category. Hopefully the good that comes out of AFRICOM will prove the first group wrong and defeat the latter.
Side Note: As noted before, Egypt is the only African country not under AFRICOM. The reason for this is that Egypt is culturally more like Asia than Africa, and so are its problems like the Muslim Brotherhood and al Qaeda.