Now that everybody is using, I started twitter thing. It's very simple but integrated very well with IM and SMS. Very nice.
Integrating web app with IM is a fantastic idea and Vox Watcher is one of the example that our David Davis has created. Check it out if you'd like to be notified your friends updates via IM (gTalk).
Speaking of realtime messaging, my friend Kenn launched Comet-based online chat service (it's like IRC 2.0) Lingr and they announced the API for it. I've been hacking the API using Perl and so far I came up with some cool bots and IRC-Lingr proxy etc.
Looks like realtime messaging is the way to go ...