I'm using archlinux. It never auto-suspend before a recent system upgrade(maybe I updated the kernel?). I think it is related to laptop-mode or acpid, so I stop them: /etc/rc.d/laptop-mode stop ...
The only way I can wake up my laptop (HP Elitebook 8460p) from suspend is by pressing the power button. Neither the built-in keyboard/mouse nor the external ones (connected via USB) wake the laptop ...