Everyone has posted links to this story but I believer it's import enough to repeat.
I love Glocks but only if they have the right holsters. In fact, I have several firearms that do not have a manual safety.
It's Tactical has a great case study regarding an accidental discharge. This story is a non-lethal accident but illustrates a lesson we can all learn.
"Editor-in-chief’s note: We’d like to thank the anonymous individual who came forward with this important information and allowed us to get it out to everyone here at ITS Tactical."
--Go over and read it. It's worth it.