I have the 13" new Macbook Air and an iPad. So appreciate your thoughts on this. I have a daily routine which includes walking to a cafe about 1.5 miles away and back and spending time their over coffee writing and reading. The iPad serves me pretty well as it is 1/2 the weight and every pound counts when you are exercise walking at some distance. I do sometimes bring my Apple keyboard (11 oz) which negates most of the weight advantage though and find it awesome when I need to write a 1/2 page or more like a blog post. The reading and fun of the iPad can't be beat and fun is not games as it is using touch without the keyboard distancing the experience. However, I agree with the multitasking, organization and file management items especially. One major advantage of the iPad right now is the apps. There are so many useful ones for specific purposes that I don't really want to be without my iPad anymore. But usually I choose between when out and about and the iPad mostly wins that battle. Also, I do carry an iPhone 4 that can serve as an adjunct in the apps department when I'm iPadless.
MacBook Air or iPad: Which Should You Buy?