While altruistic, compassionate acts are the very lifeblood of peace, I believe strongly in the power of words both to pacify and to incite, especially the words of those who are in the position to speak to the world. The act of speaking diplomatically is surely difficult to measure, but by the very choice of such a person the committee is making a statement about the importance of language in forming relationships and creating understanding. Yes, no lasting effects have been seen yet, but by the time they have, the impact of those original words may be untraceable.
That's not to say that I don't recognize the controversy. I don't necessarily even agree with the choice. But I find it appealing how unexpected the Nobel Committee's decision was, and how by it's very "huh?" factor it gets people thinking about what peace means and how one's impact on peace can be measured. The choice is provoking, right? And being provoked into thinking about the meaning of peace may not be such a bad thing these days.