Nope. He'll donate the shares. Charities are tax-advantaged. It's generally better[1] for them to take the shares and sell them than to sell the shares and donate the proceeds.
[1] better in the sense that more money goes to the charity and less to the government, and better in the sense than the charity can hold the shares and sell at an advantageous time.
Edit: I just remembered, I think that Bill Gates is doing it in the opposite way, by liquidating and donating cash, so there may be some legitimate cases when donating cash instead of stock is preferable.
