Comment 15 for bug 860485

Ok, found a workaround (not clean at all, but that's the only thing I have now) :
- edit /usr/share/polkit-1/actions/org.freedesktop.upower.policy
- replace <allow_active>yes</allow_active> by <allow_active>no</allow_active> for both actions (suspend, hibernate)

I think you don't even have to reboot, the followindg test seems to indicate the modification is immediatly taken into account :
$ pkaction --action-id org.freedesktop.upower.suspend -v
org.freedesktop.upower.suspend:
  description: Suspend the system
  message: Authentication is required to suspend the system
  vendor: The UPower Project
  vendor_url: http://upower.freedesktop.org/
  icon: system-suspend
  implicit any: no
  implicit inactive: no
  implicit active: no