Am I the only one who thinks Kakashi did something indecent to get the sharingan?
I always thought that Kakashi sacrifised his friends (probably Obito) to get the eye, and then he realized it was't worth losing his friends, and that's why he can preach to Sasuke...
i guess it could have been something like this:

Obito (half dead): help me, Kakashi!
Kakashi (after killing thier enemy): my, my, you're almost dead, shouldn't let that eye go to waste...
*field surgery done by Kakashi, obito dies"
kakashi (on his mission report): Obito died and told me to take his eye..
Kakashi (a day later): Damn, i'm bored, i shouldn't have killed obitio *whine*.

I mean, it feels right to him to have done something stupid and losing his precious people becuase of that, it makes the Sasuke -ITACHI\KAKASHI role model thing much stronger...