Just as they might be setting up the lizard, there's been rumours of cletus kassidy (not carnage) being in it too. That pisses me off though, because if they have carnage before venom....
As for anyone bitching about venom and carnage being in a spider-man movie before some of the older villains, go fuck yourself. They're easily among the top villains in the comic's history because they fucked with him so much. Of course, they'd have to have spider-man find the symbiote first and use it for a while and then the rest happens, so it would be stupid to put it all in one movie.