Boulder, Colorado, 2011
I consider this talk the holy grail of interaction design.

The video recording (62 minutes)
some notes at Cybork Anthro Wiki
From my own notebook: According to Bill Verplank each user interface is either plan or map. A plan UI provides instructions to accomplish a certain task, while a map user interface shows the entire landscape (metaphor!) and leaves it up to the user to form a mental model and make her steps. Another example: for desktop applications, the menu structure is a map user interface that presents all possible commands – on the other hand a wizard is a plan UI because the user is guided to take the commands in a predefined order. Both flavours of UI are valid approaches for certain scenarios. But they provoke a different kind of user experience. /via A Brief Chronology of the Chronoscope Universe
And my photos from a BayCHI meetup: Bill Verplank Sketching Metaphors 2008 /photo set