they also seem to think that "black"/"african american" and "arab" are mutually exclusive categories. "arab" is an ethnic group, not a race. in fact, the arab ethnic group includes people with a wide range of skin color, ranging from what we would consider "white" to "black" to everything in between. i've seen arabs in syria with skin as pale as mine, i've seen some with red hair and freckles. and i've seen arabs in egypt with skin as dark as i saw in kenya.
of course, the fact that some arabs are black, doesn't mean that obama is an arab. it's rather well documented that his father was a luo, which is a distinct ethnic group from the arab. (luos are nilotic, which is part of the nilo-saharan language family, whereas arabs are semitic which is part of the afro-asiatic language family) not that i expect the morons who listen to rush will be able to make such distinctions.