If this was first season Lois, she probably would have no qualms about revealing it. She was hungry for any type of story that would get her a Pulitzer that season. S1 Lois would not think twice about the consequences. Second Season Lois would probably think twice, primarily because she has gotten to know Clark and his parents, and anybody associated with Superman, his parents and herself included (though she probably wouldn't necessarily think of herself as in danger) would be threatened by Superman's enemies if he was outed, so S2 Lois would probably not out him. Personally I think around Great Green Glow of Home is where Lois would start to make that turn, because if you remember, she had a perfect oppurtunity to expose Superman's weakness to Kryptonite and she aquiesed and buried it.
