CNN has video of remarks John McCain made in Jordan, where he accuses Iran (predominantly Shia) of training agents for Al Queda (Sunni) and sending them into Iraq. See the two minute mark of the video.
Several blogs are reporting that Lieberman then corrected McCain by whispering into his ear, and he amended his comment to say Iran is training extremists. That is the version being carried in AP stories. It's nice when the press allows a candidate to gloss over such a bad mistake.
This man has no right to be president if he can't distinguish Shia and Sunni.
Update: After this post went up, the AP article in the link has magically transformed into a story on McCain's error. It's likely there were just too many reports on McCain repeating the lie three times before Lieberman finally corrected him, so AP had to report it.