At the MacWorld keynote this morning Steve Jobs saved the best for last. Of the 4 major things he spoke about, the final thing was the announcement of the crazy-small MacBook Air. This is the world's thinnest notebook, sporting an LED edge-lit screen, custom Penryn processor, and all that weighing only 3 lbs. Small enough to fit in an envelope: (Steve carried it out on stage in an envelope actually.) MacBook Air specs: A claimed 5 hours of battery life. The battery actually consumes about 2/3 of...