Blek le Rat, one of the early pioneers of stencil graffiti, is giving a free two-hour lecture at 2pm today as part of Free University at Viracocha (21st and Valencia):

The Free University Art School is very fortunate, and proud to present the very prolific street artist Blek le Rat on his journey around the world. He stops here with us for an extensive two hour presentation, sharing his masterful stencil art with the people of The Free University of San Francisco. Blek will tell his story, share his insurgent spirit, show his work and may even create some stencil art live in person.

Hot shit!  Find out more info over at White Walls Gallery's blog.

[Sorry for the late notice, I only just found out about this myself.]