The key to rebuilding Haiti will be in logistics. The building code in the Caribbean has to be strict, as the climate is often subject to powerful hurricanes and sometimes earthquakes.
Prefab building can be quick, but may be dangerous, as most of the materials used for such structures are typically wood and softer fibers. Concrete, steel and rebar should be the order of the day.
Structural engineers should also be consulted, to create structures with room for swaying, in the event of a future quake. Seismology surveys need to be done, to avoid rebuilding on dangerous fault lines.
A centralized, organizational committee should be formed and issues of import duty, tax and any other VAT mandates (materials) will have to be thoroughly mulled over, lest it make the rebuilding process more tedious and lengthy than necessary. Haiti's damaged areas can be rebuilt and in good time, but a very good plan needs to be on the table.
Thus far, over a billion has been raised, but more is needed.