The color coded bit seems utterly useful. Again, when applied to groups, it becomes a possible killer app. The contacts I’d track on the weekend might be different than those I’d track during the week. Actually, we should test Jaiku with our little group…

I think the best idea in this space is Jaiku. I just checked their site before writing this post, and it looks like Google has snapped them up. Interesting — I’ll bet you see their ideas incorporated into the Android system. Check out their site.

Lots there with the activity streams, blog aggregation, etc. Both Twitter and Jaiku are related in that 1) they ‘re mobile phone friendly if not centric, 2) they help you create groups of contacts, and 3)they try to get you to answer the question, “What are you doing/thinking about right now?”

But the concept from Jaiku that really resonated for me was the following: they were bringing the usefulness of IM’s green=available / red=unavailable to contacts in your mobile phone. Imagine being able to flip on your mobile, go to a contact, and see if right now that person is: on the phone (“Busy” in IM), in a meeting (“Away” in IM), have their phone turned off (“Offline” in IM), or ready to talk.

Now that’s obvious and useful as hell. Does the iPhone do that yet?