I noticed that another script is using a sort of grace time before it sends out a notification.

This is a simple delay time before a notification is being sent. The reason is that a spammer might hit and an admin may remove the spam comment within the delay time so that no notification will be sent to the subscribers.

I had this problem with some wordpress comments I made in a very popular blog. I received a lot of notifications about penis enlagements... and when I went back to the blog posting the spam comments had been removed. (So I could never read them. )

So the ideal would be an adjustable delay time to give admins a chance to remove spam before notifications are being sent. This would be favourable for this
http://wiki.geeklog.net/index.php/SoC_improving_comments_2008#Notifications and also for all others like the forum.