Ping.fm is a simple service that cuts out the middle man when it comes to posting to your social services such as Facebook, Twitter, Jaiku, Tumblr and Pownce with more being added soon.
juhu is a small mac os x application (10.4+) aimed to be a client for the jaiku web service. looks pretty promising but for now I'll stick with twitku.
I surfed over to Jaiku.com annd spent a few seconds looking at the big map on their homepage, the one that looks like Twittervision, in which new messages show up on the globe as they're posted.