There are conflicting reports, as detailed in the live updates at The Telegraph.
Updates: I’ll wait a bit before updating the headline, but it appears he’s dead (photo at The Telegraph link).
DEBKAFile says he’s dead, killed in NATO airstrike near his hometown of Sirte.
PJTatler has al-Jaeera video of what appearst to be dead Gaddafi.
Libya’s Prime Minister confirms death, according to ABC News.
This video seems to show that Gaddafi originally was captured alive, and then was killed.