I see a friend's id in YM as offline but when i view my address book his id has a smiley face. How come?

Probably because he has his messenger status to invisy.

I see a friend's id in YM as offline but when i view my address book his id has a smiley face. How come?
you have the option as appearing offline if you so choose
Reply:It's possible that there is some site lag (he signed off a couple hours ago, but the website hasn't registered that yet), or that he is signed in as "invisible" on his IM. There's also a possibility that he blocked you, but let's keep this on the positive side, eh?
Reply:He's logged into yahoo(for mail, or answers, or something), but not the messenger.