Conversation-style Private Messaging
 

I'm sure you've all used Gmail at least once in your life. Then you're probably familiar with how simple their conversation-style email system is. You don't have to scan through quoted replies or figure out what was in reference to what. Instead, you simply have the messages arranged in a chronological order, and you can go to the latest one. Or you could see the last thing you said.

Well, why not de-clutter this forum's private messaging system by putting out conversation style private messaging, just like Gmail?

Here is a great example from Yelp:
http://www.maxsavin.com/yelp.png

Think about it.. could be a great mod, or a great way to simplify the vBulletin experience.