Very, very sad indeed. I had far too few chances to interact with Bill, but when I did, they were always incredibly memorable.
One of my favorite quotes came at the SV Angel CEO conference a few years ago. When asked about culture, Bill said: "Culture is not about the free food or the ping pong tables. Culture is about how you treat your people and how they treat each other."
Rings very true to me. My condolences to his family, Bill was a great man.