There was a fascinating story today on the BBC (http://news.bbc.co.uk/2/hi/africa/4267846.stm). Senegal is upset with Gambia as Gambia has raised the cost of ferry crossings across the Gambia River. The Gambians also harassed a group of Senegalese soldiers who were shopping in Banjul while waiting for a ferry boat.
A geography refresher: Gambia covers both sides of the river crossing the middle of Senegal. It is truly a relic of the European colonial era. The British wanted the port of Banjul and the river. The French wanted Dakar and the rest of the territory.
Gambia survives largely because of its geographic position and ability to control a big part of Senegal's transportation infrastructure. It is ironic that the people are ethnically identical. The Senegalese and Gambians speak the same native languages. The only difference is one has a French style government and the other a British style government.
I really hope that the two countries don't go to war or experience a long period of disagreement. They almost merged back in the 90's. That really is the best logical outcome. I lived two years in Senegal, in Thies and really got to appreciate the country. I also did a short (three week) consultancy in Gambia, studying the fuelwood economy. These two countries, a single people artificially split in tow, really need to work this one out.