well. Steve Jobs showed it best during the WWDC. He was showing what the competitors (MS) were working on, and showed video of some cows sitting in a feild, then he showed what apple has been working on, and showed a sleek, powerful panther. I mean, a PANTHER would destroy a cow.
oh. as for the name, i guess they code name their projects based on areas close to them. Longhorn, Whistler, BlackComb. They are all like ski resorts & mountains near MS Headquarters.