A lot of wealthy people are joining Buffet and Gates in The Giving Pledge, to give the majority of their money to philanthropy or charitable causes during their lifetime, or in their will. Some of these folks are divesting themselves of their wealth while they are living, so there won't be a fight over it after they're gone, but I have to believe that those who are leaving their money to charity after their death are smart enough to discuss their wishes with their families, and have wills that can't be broken.
I'm all for this sort of giving. People really should earn their own living, and make their own way in the world. Once your rich family raises with you all the privileges that comes with being born wealthy, you should be armed with a great education, and plenty of contacts. There's no reason kids who come from rich families shouldn't go out on their own, and make their own fortunes, like everyone else.
More than that, I believe that those who earn great wealth have an obligation to give back to the society that allowed them to do so. Dedicating a huge chunk of their wealth to philanthropy or charity is a great way to do that.