Well, I can report that Time Machine (the new back-up & restore utility for Mac OS X) works.
My 364 day old MacBook suffered a complete hard drive failure, only TWO hours after completing my first full backup. I hustled to the Apple store right away, so I didn’t miss my one-year warranty window. I had my MacBook back in 3 days, fully repaired.
I installed Leopard, and was given the option of restoring from a Time Machine backup. It worked seamlessly — two hours later, I was back in business with a full restore.
Time Machine is a great example of simple & usable design. Compare it to the backup utility on Windows — the simplicity is obvious, once you see it.