New world African and Hispanic admixture studies

"Characterizing the admixed African ancestry of African Americans" finds American blacks:

are admixed in their African components of ancestry, with the majority contributions being from West and West-Central Africa, and only modest variation in these African-ancestry proportions among individuals. Furthermore, by principal components analysis, we found little evidence of genetic structure within the African component of ancestry in African Americans.

A study to be published at PNAS reconfirms a number of unsurprising findings about Hispanics. A more detailed breakdown of the Caucasoid componenet sounds like the most interesting aspect:

European migrant contributors were mostly from the Iberian Peninsula and Southern Europe. Evidence was also found for Middle Eastern and North African ancestry, reflecting the Moorish and Jewish (as well as European) origins of the Iberian populations at the time of colonization of the New World. The Native Americans that most influenced the Hispanic/Latino populations were primarily from local indigenous populations.

Update: "Genome-wide patterns of population structure and admixture among Hispanic/Latino populations" is now online.