Yeah, I know that you can use the status bar to display messages.
But, to me at least, that doesn't seem intrusive enough.
It's always there, and it doesn't grab your attention when it needs you to know something.
I have a vivid imagination of a "message box" that can be display in any view, which pops up for a few seconds and then closes, and which carries important information (something like the Gmail status messages you get when you delete mails, for example).
Then, the editor could help new users by popping up helpful messages whenever they do something that might warrant more explanation.
For example, the first time someone does a multi-selection (which is going to be new to most people), the message box can pop up and say "You made a multi-selection. For more info, click here" or something along those lines.
Anyway, that's just a dream of mine for an editor that actually helps the users learn all its awesome features.