WWD screencast: How to use Google Calendar appointment slots

Google (s goog) has rolled out appointment slots, a useful new feature for Google Calendar that allows users to publish available appointment times on a publicly available calendar that other users can then book. For example, a manager could use appointment slots to indicate available times for meetings with team members.
Appointment slots are shown on a booking page, which you can embed on a website or share with colleagues or clients. People visiting that page will then have their own personal calendar overlaid over the available appointment slots and can click to book a time; a shared calendar event is then created for both users.
Here’s a short screencast showing how to set up appointment slots and how the booking process works:
Google Calendar’s appointment slots are easy to use and should greatly streamline the process of booking appointments, eliminating email back-and-forth. However, unlike dedicated meeting scheduling tools like TimeTrade, Tungle and Setster, which also offer this kind of appointment-booking functionality but only require the person advertising their availability to sign up for the app, Google’s feature requires both the person broadcasting their availability and the person booking the appointment to use Google Calendar. So while appointment slots will probably be very useful within companies where everyone is using Google Apps, it’s not going to be suitable for, say, a personal trainer offering appointment bookings on a publicly accessible website.
Note: While I have access to the appointment slots feature on my Google Apps account, I don’t yet see it on my personal Google Calendar, so it may be that it hasn’t been rolled out to all users yet.