I like Jaiku.
I also think you need to “do” Jaiku for a fair amount of time (and commitment) to get some real value from it.
There is value from incidental chat, what is incidental for me, may be new and innovative for you and vice versa.
Here’s an example of how useful Jaiku is to me.
Lils mentioned Bluetooth which reminded me I had not got the link to some Bluetooth software that she had mentioned before in a (live) training session, so I asked her.
Not only did I get the link, but an affirmation from (Gary at) Weston College on how they were using it successfully.
Personally I think of it as a more informal Champions mailing list with the added benefit of RSS feeds.