Smallville writers Alfred Gough and Miles Millar said that there could be a link between the Superman Returns movie and the WB series, "We had a discussion with Bryan Singer and even if we're kept to the secret for the moment, we can tell you that something's going to happen in the fifth season of Smallville that will have an impact on the Superman returns movie".
Here is a description of a scene being filmed for the new Superman Returns film:
"They were filming a scene outside a building which they converted into Metropolis General Hospital. This was reportedly the largest scene they'd be shooting for the movie, with around 1,300 extras being employed for the scene. The extras were used as crowd, standing around outside the Hospital, holding banners and waving flags. The banners read, "Save Our Superman", "I love Superman", "Superman Don't Die!", "God Speed Superman". There were also dozens and dozens of flower arrangements lying in the park (as if in tribute for someone who was sick or dying)", he says. "I'm assuming this means Superman gets very badly injured (or possibly killed) during the movie, making it necessary for him to be taken to hospital".
So this could be part of the death of Superman that is rumoured to take place in Superman Returns!