Another thing the MacBook Air will hopefully force out of developers is to hit disk less often. The flash disk has a limited number of writes, and while the calculated age may be around 12 years (I can't find this link) because of the relatively low number of writes being made up by the same block not usually written all the time with 64 GB to choose from, it's possible to shorten it dramatically just by hitting disk all the time.

If a hard disk fails after five years, it's usually because it's five years old, and to a certain limit you can't fasten that onset just by being rough with it. Not so with flash disks.