Mormonisms' brothers

I've heard for some time that Mormonism considers Jesus and Lucifer to be brothers, but suddenly feel compelled to post on it now that I see Andrew Sullivan has found a defense of this doctrine right on the LDS website. Surprised me, as I've in other contexts that Mormons can be secretive about the weirder beliefs of their founders. Let's keep in mind, though, that Mormons may believe Jesus and Lucifer were brothers, but Christians believe that Jesus was God's son.