Hold the phone

You don't have to be a l33t-nerd to know this guy. You don't have to smell of silicon to know what he did. You don't even have to know all your keyboard shortcuts to know his name, because he made it possible for you to run your computer with your mouse.

He resides somewhere in Washington, but if you wear your glasses right, you know he is pretty much everywhere.
He is probably part of your computer's operating system, or your web browser. He might even be in your swank ol' HTC cellphone. He's probably even with you right now, as you read this. He is present here, as I write this down.

But now, he'll be everywhere but at Microsoft. He sort of retires, today.

His name is William, but you call him Bill.