It's not at all clear to me how, whether, or when we may start limiting Kelley's exposure to various kinds of media, however an interesting article related to such things crossed my desk not long ago. See You Grew Up Playing Shoot'em-Up Games. Why Can't Your Kids? for the full context.

One particular approach mentioned there is the "LEGO Rule":

The Lego Company, it seems, has a policy of not producing toys that replicate 20th century weapons. "You can have swords, and you can have laser guns in space, but no actual 20th century guns," Anderson says. So his four children can play games like Halo, since it contains only futuristic, fantasy war, where you're killing only green- or blue-blooded aliens. The same goes for Roman swordplay titles. "But it clearly walls off Grand Theft Auto."

(I e-mailed Lego's spokesman Michael McNally, and he confirmed the company's Solomonic logic. Lego, he wrote, agrees that good-versus-evil combat "is at the root of children's play scenarios, and we believe is an important part of a child's exploration of the world." But they don't want it infecting the children's perception of the real world around them, so the solution is to place it decisively in the realm of fantasy.)

As I said, no decisions yet, but this offers a balanced and reasonable approach that I like. Just food for thought at the moment.