Few people can call their boss their friend. In my case, he was both and more. Bill was a guy that I could talk to about anything. He was my mentor and opened doors for me in ways that I never thought possible. He's leaving Microsoft and I believe Microsoft is the worse for it.
You can read a little about him here:
Bill hired me into the SQL Server team. He was my GM when I was just getting my feet under me as a developer. Later he was there when I needed a formal mentor. He was the one that provided the opportunity for me to begin a new business at Microsoft and supported the effort throughout the initial business plan development through to where we are today, building a brand new product in Office. There aren't a lot of people at Microsoft that get a chance to do something like that.
Thanks Bill and good luck!