Carl Sjogreen, from Google, talked about Google Calendar development. Rakesh Agrawal took some notes, from which you can find a lot of interesting things:
Why did Google choose to build a calendar tool? Because no solution was very good and there was little innovation in this space.
How should Google Calendar be? Fast, simple, easy to share, visually appealing.
What's the biggest competitor for Google Calendar? The paper, because it's easy to carry with you, doesn't need a computer or a password.