Yesterday's Washington Post had this story on the African diaspora (especially Somali and Ethiopian) in the DC area and its activism in the current presidential race. As one would expect, this group is extremely enthusiastic about the Obama candidacy. The question of interest is whether their numbers are large enough to make a difference in any state.
To get a sense of the size of various immigrant groups in the U.S., this study by the Center for Immigration Studies is a good resource. In glancing at some statistics, we note that immigrants from sub-Saharan Africa make up only about 3% of the total U.S. immigrant population--they are dwarfed by immigrants from Latin America. Hence the obvious focus on the Latino vote. However, the Post story notes the possibility of there being 10,000 Ethiopian voters in Virginia that Obama could pick up. While that doesn't seem like much, consider the margin that Democratic Senator Jim Webb won by in his defeat of George Allen in 2006--9,000 votes.