Iceland has intrigued human population geneticists for some time and Icelanders are one of the most studied human populations because of their relatively small population and relatively large degree of isolation. These two features combine to give genetic drift more power than in most populations. A paper in PLoS Genetics this month spells out exactly how important genetic drift has been. There's a report on the paper here.
In the case of Iceland this means that genetic drift is a very powerful force in shaping variation, specifically, in increasing the rate of extinction of haplotypes and bringing to fixation other haplotypes.