Thanks for posting–you raise an interesting point here that is perhaps best resolved by looking at the two definitions closely. (By the way, my source was the CIA World Factbook.)

Market is most often referred to as a skerry, and in fact is a tiny, uninhabited patch of stone that two countries have roughly divided into two halves. There are no signs of any occupation other than an abandoned lighthouse.

Sint Maarten on the other hand, is currently, and has long been occupied by people and while still a dependency of the Netherlands, does have its own government and a local economy, along with an infrastructure to support communications and transportation networks. In this sense, a different geographical beast.

Not according to wikipedia: http://en.wikipedia.org/wiki/List_of_divided_islands