Why does a plane with an image texture show as black in Cycles? I created a plane and added a Diffuse Material with an image as the texture, and a single lamp above it, using all default settings otherwise. Strangely, the plane appears as black in Cycles. I can't figure out what I could have possibly done wrong.

Do I need to tweak something? (Or is it normal for Cycles to treat a Plane with an image as not being illuminated (if there are no other objects in the scene)?)
Add some Texture Coordinates! Generated works out of the box, and UV is even better. All pretty standard stuff. :)