Honesty is very important. I've ended friendships because a person/people don't stick to their word. If you tell me you're going to call me, then you'd better call me. I feel that if you lie about small things, you don't care about the person you are speaking to. How hard is it to pick up the phone and call? Also if you lie about small things, you are probably lying about the big things too.
Honesty is always really important. You shouldn't lie no matter what.. If it's a small lie like saying you like someone's shirt when you don't then it is okay but if it's lies about where you were or what you were doing then that's bad :)
I rarely lie but I'm not sure how noble my reasoning is. If I respect somebody I wouldn't lie to them, and if I don't respect them I couldn't be bothered what they think so, equally, I wouldn't bother to lie to them.
When people lie to me I don't reject their friendship but I pigeonhole them in the "not-to-be-trusted" box and treat them accordingly. I don't allow such people to know any intimate details of my life.