UK retailer Argos has published the first images of 76003 Superman: Battle of Smallville.
Click through on the image to see the hi-res version on flickr. You'll find the hi-res white-background version on the set details page. I can't quite read the text under the minifigs, but it appears to contain Superman, General Zod, Colonel Hardy(?), Faora and Tor-An.
A better image of 76002 Superman: Metropolis Showdown was also published, so I've added it to the database.
Presumably the fact that they've beed added suggests that they'll be available soon.
Thanks JustTooGood and CapnRex101 for the heads-up