I realize that this is not the origin of Sen Obama's name, but Barak in Hebrew means "lightning", and appears in the Bible. I only bring this up because Barak and Barack are homonyms.
That doesn't have mean that they have the same origin. When I read Barack, my first though was Barak "Lightning" too, but there are a-ling sounding names tghat have nothing to do with each other (example click on Naomi)