Just ran across this: I/O Brush, did by Kimiko Ryokai, Stefan Marti, Rob Figueiredo & Hiroshi Ishii at the Tangible media group (MIT).

I/O Brush is a new drawing tool to explore colors, textures, and movements found in everyday materials by "picking up" and drawing with them. I/O Brush looks like a regular physical paintbrush but has a small video camera with lights and touch sensors embedded inside. Outside of the drawing canvas, the brush can pick up color, texture, and movement of a brushed surface. On the canvas, artists can draw with the special "ink" they just picked up from their immediate environment.