Sadly, there is a long tradition of strife and poverty in Haiti, poorest of western nations. I was there in 1976 on a diving expedition to try to find Colombus' Santa Maria entombed in the barrier reef 5 miles off Cap Haitian on the north coast. Even then there was a practice of rolling 55 gallon drums over the airstrip to deter an air invasion from neighboring DR. There were army officers all over the airport with grease guns and the impression that life was cheap came readily across. Haiti has been in tumult on and off as far back as the Napoleonic Wars and before. The USA first invaded the island in 1915 to try to deal with one of so many revolts. On it goes. When I was there, our former Secretary of State, Young managed to insult Baby Doc and came close to having our expedition put under house arrest at the Roi Christophe. This same "diplomat" managed to have our visas cancelled for a unique UW archaeological investigation of Cuba with a mindless insult to the government in the same year. Anyway, that is a small bit about Haiti, there is much more to tell.
More about the violent, colorful history of Haiti at:
http://en.wikipedia.org/wiki/History_of_Haiti
Then there is the western part of Hispanola, the Dominican Republic. The DR is managed quite differently than Haiti. It has its share of strife but is largely more of a success story in some ways than Haiti. It even shows up in the land. Haiti has been ravaged by mindless clear cutting and charcoal manufacture resulting in erosion, catastrophic mudslides and the like. You can look at aerial photos over the border and conditions can be night and day on either side of it.
Bottom line, I wouldn't expect an invasion/revolt to spill well into the DR anytime soon. Of course I could be wrong but this sort of social unrest and chaos has been underway in Haiti periodically for a very long time. I would be more concerned about getting clotheslined by some nitwit in the crowds offshore or being taken out by some dufus on a moped. Eagle is right, you can easily get travelers diarrheah from all the normal third world sources there. It can be crowded and a bit overpriced compared to a few years ago. Then again there is that great wind when it blows and those outstanding waves over the reef. You got a good airfare, hope the wind blows and you have a blast! I'd like to join you but we're heading west this time. Let us know how it goes there.