The Vinson has actually been there for about a day now - it was immediately sent from Virginia after the quake, and got there the next day. A coast guard ship is actually handling all the air traffic control duties for the airport, as the tower was too damaged to be used. They are rushing in some US Marine engineering and road building units to try to get some of the roads clear. There is a huge problem that the harbor is too messed up to use (wharfs are underwater, cranes and other equipment to offload ships have been destroyed, and the roads leading from the harbor to the city are too messed up to use). They have actually had to turn away cargo ships which have arrived carrying food and emergency medical supplies because there is no place for the ships to tie up and no way to unload them.
The airport is another huge issue. It is a small airport, and simply cannot handle the current load of cargo jets carrying in equipment and personnel - and again, not enough equipment or space to offload and store the desperately needed goods - and the roads are too messed up going from the airport to the city for large truck convoys. So all of these charity groups have jetloads of goods and people ready to go - and they are grounded here in the US because the airport in Haiti is overwhelmed.
So frustrating - how many people are going to die because those ships cannot offload their food and water and because the jets carrying medical supplies are sitting on the tarmac in the US?
The last I heard they were thinking about sending in US Army Paratroopers! That is how bad things are down there. Paratroopers are true badasses who are extensively trained to operate on their own fairly independently behind enemy lines. This, of course, would include living off the land in really bad conditions and performing basic first aid. So they are not there to fight in any way - they would be there because they are tough as titanium nails and might be able to help people under impossible conditions in very difficult to reach areas of the country. A lot more than just the capital city got wiped out, and it is nearly impossible to get to some of the other areas, and the people there also need help.
It sounds like they might be sending down everyone they can. The government has put tens of thousands of reservists on notice that they could be called up at any moment. A friend at work was telling me that a friend's son just got through army basic training as a medic a couple of weeks ago - he was expecting to be sent with his unit to one of the war zones. They are being sent to Haiti instead.