One of the nicest things about the 10.3.x world was the notebooks went to sleep so well. Shut the lid, go to sleep.
When Apple introduced OS X 10.4, they broke this. A number of processes don't respond properly to the sleep command -- including background data indexing (spotlight). It's easy now to close a laptop and cart it off -- with the drive running.
Now an Apple kb article admits the inevitable (without apology) -- you can't rely on the sleep mechanism to work:
Wait for your Apple notebook to fully shut down before you close the display.
This was a real screw-up in 10.4. I wonder if it might be fixed in 10.5.