Two small titbits over the future of Supes.
First off Brandon Routh, who was excellent as both Superman and Clark Kent in the last outing has said that his contract to play Superman has expired and even though it's gone he would jump at the chance to play the man of steel again. I would hope they would return to Routh first as he really was great in Superman returns.
Secondly, the custody rights to Superman have been ongoing in court for some time now and Warners vs DC/Seigel have been ruled on by a judge. Warners now have to put a Superman film into production by 2011 or DC can claim damages on a no reversal of rights for Warners failure to produce another film. So expect a fast track on another Superman film next year. Good news for Brandon Routh i think.