Post highscore to Facebook

I would like to add an option in my iPhone game to "Post HighScore to Facebook".

I suppose it would ask the user for Facebook login details, then post a generated message to their wall, maybe with a picture, or little icon next to it.

I guess there may be some issues regarding privacy, and I am a bit concerned that people might be scared about the game "Infiltrating their Facebook". That is also something I would like other people's opinions on.

I'm wondering if this can be done, and if so, what would be involved in implementing such a feature?