This is really good about Debian, its 3.1 version (old Stable) is still getting updates, and maintained, which are great news for all those servers which are still using the old Sarge.
You can get the new updated CDs from here
Those who frequently install updates from security.debian.org won't have to update many packages and most updates from security.debian.org are included in this update.
So if you usually run
you should not worry about anything.
Read the announcement here