This should surprise no one: U2's "Ordinary Love" has leaked online in advance of its official premiere. From what we understand, it was recorded while the song played over the credits of Mandela: Long Walk To Freedom. I don't know if this is the original source, but you can hear it (amidst talking movie goers) via this Soundcloud upload.
UPDATE: That link no longer works, but the song is still available here.
UPDATE #2: It looks like there's a game of Whac-A-Mole going on, as now that second link is also dead. Soundcloud's easy "repost" feature makes it easy for other users to keep spreading files from account to account, so this could get ridiculous if U2 and/or the label keep getting these removed. In any case, two more here and here.