GIM - The GMail Instant Messenger

My friend was working on a computer that didn't have an IM installed, so we sent tiny emails back and forth to each other. We were both using GMail, and there is a wonderful (free) "GMail Notifier" that sounds a little bell and displays an excerpt whenever a new mail comes in. I couldn't help by notice the similarity between this modality of communication and instant messaging -- they're very close...

I'm going to coin a name for this kind of communication: EM (email messaging).

I wonder if EM can evolve into something really new. It's got a couple of good things going for it: the ubiquity and platform-independence of email, and (almost) the instant communication of IM (especially with good supporting tools in place like the GMail Notifier). Hmm . . .