here's a very clark kentish picture of jon hamm from mad men.
		 
		
	 
Yeah, I don't know what it is, but Hamm just screams Superman to me.
Have you seen him on the cover of GQ -- he looks like Alex Ross' Superman come to life
 
You don't even need to put the curl on that.  The guy can act and he'd certainly bring the more established Man of Steel look to the film.
If Nolan wants to go older, then Hamm makes a lot of sense.  It's interesting some people here keep thinking about sequels, etc., but if the rumors are true, it seems clear that Nolan isn't looking at this like a franchise.  He's out to tell one strong Superman story, and that's the goal; it's a stand-alone film that isn't tied to anything.  There might be a hint towards a sequel (like in Begins) but it wouldn't be anything set in stone.  That's what I think we're going to get here.
Also, age-wise, Hamm (or anyone in their late 30s, early 40s) works because he's around the same age as Bale and I don't doubt the two would look quite good standing next to each other in a JL film.  We certainly needn't worry that our Superman can act ... and he'd really look like a Superman vs. the overly young actors we've seen.  
I'm starting to really like the thought of an older Superman.