There was a thread bemoaning the loss of the John Williams score (assuming that happens - Williams' score for the Harry Potter films has been retained despite all the different composers in the later films). But I seem to have misplaced it.
I for one am all for the idea of bringing in a new composer for Superman. I was one of the 24 people who liked Superman Returns, but while it was a thrill to see the updated version of the Williams score, I thought it was a mistake because it immediately reminded everyone of Christopher Reeve, which deep-sixed Brandon Routh from the get-go. Yeah, yeah - James Bond Theme, Doctor Who Theme, Star Wars Theme - but for whatever reasons the Williams theme for Superman is not associated with multiple actors over the history of a franchise, but with one actor. And it just didn't feel right for it to be used in the Singer film.
Whether it's Hans Zimmer or whomever, it doesn't really matter in the end. The James Bond films are really the only films of this particular type that even bother with opening credits anymore, so really all Zimmer needs to do is come up with some catchy plink-plonk to go with the flying sequences, and maybe some semi-sappy love theme for Lois and Clark, and then some generic filler music for the end credits to play while everyone files out. (Boy am I sounding cynical today or what! Part of it is due to my annoyance over being forced by crowds to exit Harry Potter and the Deathly Hallows within 20 seconds of the end music starting, when I would have preferred to hang about and listen to it.)