From Wikipedia:
''[...] In 2007, Rui Nagai composed "Big-O! Show Must Go On," a 1960s hard rock piece, for Animax's reruns of the show[...]''
So yeah. This show re-ran on a Japanese network called 'Animax' in 2007, and Rui Nagai (the man responsible for the first opening theme) composed a new theme for the show. Bringing the grand total to three opening theme songs for 'The Big O'. The third opening was just a new song, though. It uses the same animation as the second opening. Sadly, we never got this song to air in the states.
Perhaps if Toonami, for some reason, decides to re-air it they'll buy the rights to the song.
