Price being a big one also. The Macbook Air sells well, but it's also an Apple machine, people expect to pay highly for it. The last notebook fad was the netbook, an inexpensive, but still fully functional laptop. Ultrabooks are high priced, and their one big feature is being light and thin. With tablets and smartphones (sadly) taking off, is most people going to shell out $800+ for something expensive like an ultrabook?