Dave Sigafoos:
I am looking (have searched but not found) for an extension that would 'NOTIFY' the users that a page is currently being edited if they try to go into edit mode.
I'm not aware of anything that does this; and it wouldn't be easy.
The problem is that (as far as I know) MW doesn't track who is editing a page. The reason is that anyone can click "edit" (for example, to view the source, or by accident) and then just go away forever. There's nothing forcing you to click "Cancel". When you submit a change, that is when it checks whether the version you originally edited is still the latest version, or if someone has submitted a change since then.
So, to do what you're asking, you would have to do some guesswork; like checking for people who clicked edit in the last 30 minutes (or whatever). But some of these people would still not be "really" editing; and some people who are "really" editing might hold a page for longer than that. This still might be useful as a rough guide, though.
I realize that the basic philosophy is what we call 'Optimistic Locking' (rose colored glassed).
Actually, MW doesn't lock at all, for the same reason; the model is copy-and-merge, which most revision control systems use. (See, eg., CVS, ClearCase, subversion, etc.)
Ian