I’ve blogged numerous times about XMPP, SMTP, and communications evolution on the web.  I’ve suggested what I want ultimately and snippets of how we might get there.  Here, I am going to outline just briefly what I consider “next steps”.  The big ones.  Get these done, and you will have made a *huge* stride in online messaging:

1. Allow offline messages (type normal or chat) to be collected as “email”.  Gmail sort-of does this by presenting unseen offline messages in the web interface inbox.  I want IMAP access to these in the inbox and their archive.  Heck, store them in a Unix mailspool (have to store them somewhere anyway) and existing IMAP servers will just work for you!
2. SMTP messages are type=normal.  If you store offline messages in a mailspool and run an SMTP server on that spool, you’re mostly done.  Might be good to offer real-time deliver of those messages to the user of XMPP as well though.

That’s it! Sure, more can be done, but if you get the first one done I will be your biggest fan.  Do both and you’re well on your way to an evolution in how we deal with email (both from a user and a protocol perspective).  Yes, I’ve tried to build this.  I want to do it as an ejabberd module, but ejabberd is barely documented.  I’ll try again sometime if no one else does – maybe with ejabberd, maybe with someone else.