Gruber on Mountain Lion:
That mindset and development schedule — “What can we do to make this nicer by next year?” — may well be the most important thing from iOS that Apple has taken back to the Mac.
As long as Apple can keep up the pace and keep down the price, it might be the most welcomed thing to be taken back to the Mac. It’s like the frog in the frying pan. Huge, world changing updates burn users (or scare them at the least). Slowly morphing the OS, one inexpensive upgrade at a time, keeps users comfortable while still moving them toward the future.