Good point. According to my wife who worked for the local government, they where brought here shortly after the storm since Katrina made landfall just west of the Florida panhandle. The area was designated as a staging area for supplies and the famous FEMA trailers. I did see many of these trailers being delivered to the Biloxi and nearby areas which were just as devastated as New Orleans, but not too many people saw that.
It seems that way. So all they have to do is tie down the two on the ends. These were most likely leftover trailers from hurricane Ivan the year before. Many people were still receiving these a year later, all because of the massive amout of red tape to get one in you property. They were probably arranged like this in preparation for Katrina, I guess.
Hurricane Katrina 
Or is it possible this is from *after* Katrina and these sat unused and helping absolutely no one due to our harmoniously operating government?