I keep hearing talk about people expecting Lex to "turn Evil" and it just doesnt sit right with me.
There isnt going to be some life changing event that happens to Lex, and all of a sudden one day he's laughing maniacally, twisting his moustache, and tieing Lois to railroad tracks. This isnt pre-crisis Lex, or Lex from the Superfriends either, where he's going to be committing crimes just for the sake of committing crimes. It's going to be an accumulation of things over time that contort his sense of what's right and wrong on things.
Lex will, for the most part, be a man with a very skewed perspective on reality, due to a huge ego and suspect upbringing, who does things he believes to be in the best interests of those involved but namely himself. Most of the time he'll employ means that are less than honorable trying to achieve them. I think Smallvillle gave us some big time clues to that effect in episodes like "Talisman" and "Onyx". However he wont be as "obvious" as the bad Lex in Onyx was, he was more like the Joker the way he acted without the cool, calm Lex to keep him in check.