Displaying it privately to the user would probably be fine for the sake of interest. I don't see harm in that. I am leaning away from showing anything public though now, it promotes a really nice environment.

If we grow to a size of any influence or worth there is an inevitable thing we can't escape -- a third party site will popup that gives karma scores and scoreboards of all users by scraping the site. How to handle that down the road is probably something admins should be thinking about in advance so there's a plan for it.

You can always add it up manually if you really want to know.