Habitat always gets a lot of financial support after disasters. They DO rebuilding, but they do it their way.
They have family selection processes, volunteer hours requirements, local committee requirements, and need local leadership in place before they do much. Homeowners are selected one at a time, and ultimately the houses are never given away, they are sold.
Fact is, no matter what the price, some people simply can't ever afford to buy.
Additionally, in a place like Haiti, land rights are always an issue. True ownership doesn't come without decent protection for land ownership, which is hard to come by and define in Haiti.
Don't get me wrong, I believe Habitat will handle the funds honorably, etc. But they will build according to what THEY do, which is not relief work. It could take some time. There have been several times where large amounts of designated funds have poured in to the organization for efforts in a specific area where they did not have established efforts, and the money had to sit idle for many years while they developed efforts to utilize it.
I don't even know what to suggest if your heart is in helping with rebuilding efforts. Please understand, this is huge. Housing for as much as one third of the population of the entire country may have been destroyed.
The quickest impact with the biggest short term results will certainly be relief efforts with medical missions. They simply don't need rebuilding yet, they need life support. Lots of Haitians survive under normal conditions without housing- climate is quite good. But sickness, malnutrition, and disease are going to kill a lot of people.
The largest rebuilding impact will probably ultimately be a US (and other governments) relief and aid package that addresses large scale housing reconstruction to help huge numbers of people who are unable to help them selves (read- can't pay for anything).
The greatest impact you can personally have would probably be to donate money now to relief and medical missions, then plan on going to personally assist with a rebuilding effort (such as Habitat, or smaller ministries) at a later date. You won't regret it.
My plan is to do just that. I'm going to get my money as fast as possible into the hands of SOMEONE to do SOMETHING, then I will get myself down there to use my hands to bless others- probably later in the year.