NewInstance

Previously I wrote that suspend/resume was not working in Karmic on my MacBook Pro 5.1, and I posted a solution. Now I found a better solution from the Apple Users forum on Ubuntu. The advantage is that with this fix, the suspend/resume is much faster.
First you need to revert the change I suggested previously.

Then... (copied from the forum)

install a package called uswsusp

sudo apt-get install uswsusp

the package carries two nice tools: s2ram and s2disk

First of all make sure they work launching

sudo s2ram --force

to suspend to ram or

sudo s2disk

to hibernate.

I personally don't care too much about hibernation. Nice thing about s2ram, though, is that it goes to sleep maintaining somehow the proper wifi settings so that when you open up the lid again the machine is immediately connected to the internet, exactly as it happens in OSX¹. The resume takes about 5 seconds and you are ready to go.

By default gnome prompts you with the password after resume. If you don't like this behaviour, you can change it running

gconftool -s /apps/gnome-power-manager/lock/suspend -t bool false

you can of course use s2ram and s2disk as default tools. to do so, you need to replace two of the existing scripts.

sudo cp /usr/lib/hal/scripts/linux/hal-system-power-hibernate-linux /usr/lib/hal/scripts/linux/hal-system-power-hibernate-linux.bak
sudo cp /usr/lib/hal/scripts/linux/hal-system-power-suspend-linux /usr/lib/hal/scripts/linux/hal-system-power-suspend-linux.bak

and then

 sudo gedit /usr/lib/hal/scripts/linux/hal-system-power-hibernate-linux

replace what you find with:

#!/usr/bin/env bash
/usr/sbin/s2disk

 sudo gedit /usr/lib/hal/scripts/linux/hal-system-power-suspend-linux

replace what you find with:

#!/usr/bin/env bash
/usr/sbin/s2ram --force

Credits for this post: crocowhile

Luigi's notes on above post
¹: this doesn't happen to me, it seems that, before suspending the wifi connection is brought down, then it needs to be restarted on resume. There is an option in the Gnome Configuration Editor apps/gnome-power-manager/general/network_sleep which is described as "Whether NetworkManager should disconnect before suspending or hibernating and connect on resume". By default this is disabled, which I think should mean to not disconnect/reconnect. I played a little bit with it; but it seems that is not taking any effect, and every time I resume the NetworkManager reconnects to the WIFI. Suspending with the command line, this doesn't happen, and the WIFI is immediately available; I need further investigations on this. I suspect the pm-utils is playing some quirk, and I cannot find a configuration variable for pm-utils to specify to avoid this.

UPDATE: NetworkManager is fixed!

I just found that the cause of the NetworkManager to disconnect/reconnect on suspend/resume was actually the pm-utils. So I modified the script located at /usr/lib/pm-utils/sleep.d/55NetworkManager to not manage the NetworkManager. I've commented the two lines in bold:

luigi@hal9000:~$ cat /usr/lib/pm-utils/sleep.d/55NetworkManager
#!/bin/sh
# If we are running NetworkManager, tell it we are going to sleep.
# TODO: Make NetworkManager smarter about how to handle sleep/resume
#       If we are asleep for less time than it takes for TCP to reset a
#       connection, and we are assigned the same IP on resume, we should
#       not break established connections.  Apple can do this, and it is
#       rather nifty.

. "${PM_FUNCTIONS}"

suspend_nm()
{
	# Tell NetworkManager to shut down networking
	dbus_send --print-reply --system                         
		--dest=org.freedesktop.NetworkManager  
		/org/freedesktop/NetworkManager        
		org.freedesktop.NetworkManager.sleep 2>&1 > /dev/null
}

resume_nm()
{
	# Wake up NetworkManager and make it do a new connection
	dbus_send --print-reply --system                        
		--dest=org.freedesktop.NetworkManager 
		/org/freedesktop/NetworkManager       
		org.freedesktop.NetworkManager.wake 2>&1 > /dev/null
}

case "$1" in
	hibernate|suspend)
		# suspend_nm
		;;
	thaw|resume)
		# resume_nm
		;;
	*) exit $NA
		;;
esac

With this change now, from the time I open the laptop lid, it takes 2-3 seconds to wake up and be online. Wow!

UPDATE: Suspend-after-resume bug

During the resume it could happen that the mac goes back into a suspend (see gnome-power-manager bug #425411). This is resolved by the following:

1. Run gconf-editor
2. Go to apps -> gnome-power-manager -> actions
3. Uncheck the box next to event_when_closed_battery.