edit - One way you could do this would be in the 'Manage notifications' settings page have three options for each notification - Always / Locked only / Off. That would allow people to prioritise important notifications.
signal sender=:1.1 -> dest=(null destination) serial=3592 path=/com/nokia/mce/signal; interface=com.nokia.mce.signal; member=tklock_mode_ind string "unlocked"
signal sender=:1.1 -> dest=(null destination) serial=3628 path=/com/nokia/mce/signal; interface=com.nokia.mce.signal; member=display_status_ind string "off"