I was very pleased to discover that hibernating worked "out of the box" with Edgy Beta 1 on my old Compaq Presario 1690 laptop (K6-2, 128MB RAM; it really is old). Resuming worked as well, albeit there was a square in the upper left corner of the screen that was a bit corrupted-looking. Logging out and back in fixed that.
Then I downloaded some more Edgy updates and installed them, but the initrd generator never finished postinst; it just sat there. I hit Ctrl+C, and the configuration of usplash and powernowd also didn't finish; I had to Ctrl+C them as well.
I finally discovered that /etc/acpi/hibernate.sh was still running, and was waiting for "modprobe thermal" to return. I killed the "modprobe thermal" process, and the hibernate script finished running, which included starting anacron.
This is dangerous because I'm guessing that, if a new kernel package is installed, but the initrd generator doesn't finish running, the system might be left in an unbootable state. And, of course, whatever else the hibernate script didn't get to finish doing.
It's really not acpi-support's fault if modprobe isn't returning.