From the Official Google Blog:

World Usability Day, November 14, 2006, is for everyone who’s ever asked these questions. This Earth Day style event, focused on raising awareness and visibility of usability engineering and user centered design, is currently being organized by volunteers and local event coordinators from around the world. Whether a usability professional or just an enthusiastic (or frustrated) user, each participant is making a contribution to “making life easy”.

Check out the worldwide usability events map as well as the usability webcasts schedule.