I'm using Dapper.
If I click on the little Gnome power-off applet button, and then choose either suspend or hibernate, those functions appear to work as intended.
However, I've setup Gnome to do a suspent (or hibernate) when I close the lid. I do this by clicking on System -> Preferences -> Power Management. On the "Running on Battery" tab, for the drop-down list "When laptop is closed", I select either Suspend or Hibernate.
Having done that, when I close the laptop's lid I have no evidence of the system suspending or closing.
One way I do this is by starting the following Python script prior to closing the lid:
>>>>>>>>
#!/usr/bin/python
import time
while True:
print time.asctime()
time.sleep(1)
<<<<<<<<
After closing the lid, leaving it closed for a large number of seconds, and opening it again, I look at the console in which I ran the Python program. I see no gap in the sequence of timestamps printed to the console, which suggests the program ran uninterruped while the lid was closed. Thus, the system had neither suspended nor hibernated.
This bug is a pretty big one for Dapper. Breezy had a similar problem but I didn't know it. I got my non-techie brother to install Breezy on his ThinkPad, and the thing fried itself in his laptop bag beause it didn't power down like he assumed it would. This bug has hardware-damage implications.
"suspending or closing" should have read "suspending or hibernating".