The word is a certain cosmic Green Lantern character will appear in 2011's GL flick. He's not a household name, and his inclusion signals that filmmakers aren't straying from the wackier side of the GL mythos. Who is it?
According to Comic Book Movie, it's Krona, an Oan scientist whose single-minded desire to witness the creation of the universe inadvertently created the DC multiverse. Krona will appear alongside Parallax, the supervillanous embodiment of fear that was trapped for eons inside the Oans' Central Power Battery:
Another day, another Green Lantern filming report. The cast and crew of DC's next superhero tentpole franchise, Green Lantern, will be filming in downtown New Orleans, Louisiana, tonight. Several streets will be completely closed off to allow room for an Earth-based scene involving the fear entity Parallax and Krona.
Krona debuted in 1965's Green Lantern 40. His experiment spurred many an important (if totally perplexing) event in the DC universe, namely the creation of the multiverse, Monitor, and Anti-Monitor. His actions also inspired the Oans to become the Guardians of the Universe. Krona's most notable modern appearance was in 2003-2004's JLA/Avengers miniseries, in which he fought, oh, anyone who ever had a JLA or Avengers membership card.