Disable locking the screen after resuming from suspend

Start gconf-editor (press ALT-F2, then type gconf-editor).

Seach down to Apps/gnome-power-manager, then click on "lock".

You have two choices : either untick "suspend", or tick "use_screensaver_settings" (of course, you'd then have to go to screensaver preferences and remove the "lock screen" option.

And :

This will disable the locking, altogether, so you won't be able to lock the screen even if you wish to, but if you don't care, just enter these commands. The first commands just gets your current setting, which is likely false:

gsettings get org.gnome.desktop.lockdown disable-lock-screen
gsettings set org.gnome.desktop.lockdown disable-lock-screen 'true'

regards,

As mentioned in the comments, the solution mentioned above doens't work for Ubuntu 11.10. Please see How do I stop the screen from being locked on suspend? to 'fix' the issue on 11.10.