I have just upgraded my girlfriend's computer (a Dell Inspiron 6000) from Gutsy to Hardy. When she closes the lid, it goes to sleep just fine, and when opening the lid back up again, it appears to wake up, but the screen never turns back on. I've tried a few things (switching virtual terminals, pressing the power button briefly), but none of them seem to wake the computer up. We've had to shut the computer down and start it back up again to get it working. Checking /var/log/messages indicates that it thinks it's resuming, and it logged the times I pressed the power key after resuming, but never did the display show anything in that time. Before upgrading from Gutsy to Hardy, suspend and resume worked mostly fine, though with some occasion flakiness.
After further experimentation, it turns out that this only happens when suspending by closing the lid; if I suspend by using the power button on the gnome panel, the power button on the laptop, the Function-Suspend key combination, or '/etc/acpi/sleep.sh force', it suspends and resumes just fine. Only if I put it to sleep via closing the lid does it have a problem. It seems to wake up fine other than the screen; I can ssh in, put it to sleep using /etc/acpi/sleep.sh force, and then wake it up with the power button. And if I put it to sleep in any of the ways besides closing the lid, close it, and open it, it wakes up just fine. The only way it breaks is by going to sleep via closing the lid.