...is a bit like
Twitter, you know a way to message (irritate?) a whole bunch of people via either IM, SMS, or the web interface. If you listen to all the Web 2.0 twaddle it's the way forward.
I quite like the occasional bleeps of my Twitter contacts letting me know what they up to and assume they don't mind my occasional Tweets (as they're called)
Spending far too much time on the interwebs and being the sort of person that will sign up for most free things, I've gone and got a account as well as my Twitter account. Twitter can just be signed up for, whilst at the moment you need an invite for Jaiku. I've got some Jaiku invites, if anyone wants one, drop my a message with an e-mail I can send it to. First come first served.