The study reportedly shows that a few Jews started the Ethiopian community thousands of years ago, that they married local women (as was the Biblical practice), that they are a distinct population that did not have much intermarriage with non-Jews, and that sociologists who claimed the community came from Ethiopian Christians who "Judaized" approximately 500 years ago were wrong.
In other words, the study (which I haven't yet seen) reportedly backs up some of the founding myths of the Ethiopian Jews themselves. As Reuters notes:
…The Jews of Ethiopia are so [genetically] distantly related to other Jews that their community must have been founded by only a few itinerants who converted local people to Judaism and then married within the local population. It also suggests the founding was more than 2,000 years ago.
That antiquity helps explain why Ethiopian Jews airlifted to Israel during "Operation Moses" in 1984 had no idea about the holiday of Hanukkah, which commemorates events of the second century BC--long after their ancestors had left Israel.…
Update 7:05 pm CDT – Here is the relevant conclusion from the study itself, followed by the entire study as a PDF file:
The observations for Georgian and Ethiopian Jews met his- torical expectations—Georgian Jews are an outgrowth from the Iranian and Iraqi Jewish communities, and Ethiopian Jews are an ancient community that had relatively few, if any, Jewish founders from elsewhere and existed in isolation for >2,000 years. Nonetheless, the low FST between Sephardic and Geor- gian Jews suggests that the latter may have had significant contact with Turkish or Syrian Jews. The observations for the Yemenite Jews are even more surprising. Like the Ethiopian Jews, this population was founded >2,000 y ago and was thought to be comprised mostly of local proselytes, which is reflected in the distinctive clustering of the population away from other Jewish groups and the mostly Middle Eastern ancestry present in this group. However, the observation of comparable FST and IBD sharing with other Jewish communities implies signinifcant common Jewish founders in the absence of more recent genetic flow into the community. Thus, although Jewishness was trans mitted by the flow of ideas and genes, both appear to have been under selection for long periods of time.