@Emilski - In my biology class, we just got done dissecting a sheep brain, so I still have all of this fresh in my mind.
Grey matter is typically found around the outside of the brain, and white matter is on the inside. The difference in color is because of the different types of cells that make them up. For the most part, though, they have their own functions, but there isn't really a huge different in texture or anything. Black matter is in the middle section of the brain, like the article mentions. If you ever look at an MRI or some other type of brain scan, you can clearly see the black section in the middle.
Unfortunately in class we never really talked about what could go wrong with the different parts of the brain, which is what really interests me. The cerebral peduncle is involved in motor skills, too, so I wonder if somehow it is involved in Parkinson's Disease or something else like that.