And yes, this is something we need to deal with. I don't think that
disks that use contact start-stop heads care so much, but disks that use
load-unload heads (like most laptop drives, it seems) generally quote a
much lower cycle lifetime for "emergency unloads" caused by power loss
than by normal unloads done while power is still applied. It's important
enough that in some cases, like the Compaq X1000-series laptop I have,
the BIOS appears to have a power button handler that spins down the
drive before power-down when the power button is pressed and an ACPI OS
isn't running. (Holding the button down when an ACPI OS is running just
forces the power off, then you get the clunk from the drive..)
Windows XP (and even as far back as Windows 98) get this right, surely
we can do as well :-)