Human to Worgen Transformation and back in Gilneas, their starting zone (SW coast of Hillsbrad). Out of combat, you can change from Worgen to Human at will. In combat, the default state is Worgen so if you happen to be Human at the time, you will autotransform.
As of 9/13/10 Beta, both of your Worgen and Human counterparts are customizable at the starting interface.
P.S. Do NOT post shit about whatever the music is that happens to be playing while you watch this. It's not of my choosing.