cannot suspend from gnome3

[foogod]

In a recent install of Ubuntu 12.10, when using the Gnome desktop, if I try to "Suspend" from the top-corner pulldown menu, nothing happens (no error messages, no attempt to suspend, no nothing. The request seems to be completely ignored.).

I have done this successfully on previous versions of Ubuntu, and I am able to suspend (and resume) just fine when using Unity, so this appears to be a relatively new problem specific to Gnome..

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: gnome-power-manager 3.6.0-0ubuntu1
ProcVersionSignature: Ubuntu 3.5.0-19.30-generic 3.5.7
Uname: Linux 3.5.0-19-generic x86_64
ApportVersion: 2.6.1-0ubuntu6
Architecture: amd64
Date: Tue Dec 11 12:28:17 2012
InstallationDate: Installed on 2012-11-28 (13 days ago)
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Release amd64 (20121017.5)
MarkForUpload: True
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-power-manager
UpgradeStatus: No upgrade log present (probably fresh install)