According to Sci Fi Wire:
The sequel to Superman Returns will likely hit theaters in 2009, executive producer Chris Lee told The Honolulu Advertiser, while the IESB.com Web site reported a rumor that the sequel’s working title will be Superman: The Man of Steel.
Singer and Peters are in Honolulu this week to celebrate Lee’s birthday and to begin planning the next Superman film, which will likely begin production in the middle of or late next year in a location yet to be determined. Superman Returns was shot in Sydney, Australia.
Singer told the newspaper that he has also been offered the fourth X-Men movie, but said he wouldn’t have time to take on another large-scale project before the next Superman gets underway. He added that he is interested, however, in seeing the script for the proposed X-Men spinoff, Wolverine.