After upgrading to systemd a couple weeks ago the suspend functionality was broken, and required editing /etc/systemd/logind.conf to include:
HandlePowerKey=ignore HandleSuspendKey=ignore HandleHibernateKey=ignore HandleLidSwitch=ignore
After upgrading to Gnome 3.6, however, suspend on laptop lid is broken again.
It looks like the functionality is now controlled in gnome-tweak-tool, but everything there seems to be set correct (i.e. suspend on battery/power). I also tried looking for the acpi handlers, but those seem to have been completely removed.
Same here... only pressing the Power button works in my laptop.
I had the same issue with the same configuration in /etc/systemd/logind.conf and in tweak-tool as hughitt1, but after changing HandleLidSwitch=ignore to HandleLidSwitch=suspend it works fine. The Power button though shutsdown for me with the following settings: HandlePowerKey=ignore and Power button action turned to shutdown in gnome-tweak-tool
Edit to previous post:
Power button works indepedently from the settings in gnome-tweak-tool. It seems that gnome-tweak-tool has no affect at all in power management.