I just upgraded to the new gdm package (v2.14.10) that appeared today in dapper-updates and I can confirm the suspend functionality is now working for me from the gdm login screen.
-- Suspend (or hibernate) does nothing https://launchpad.net/bugs/3642 -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
