Jisko is a newish microblogging service that aims to compete with Twitter by offering an open source platform.
Jisko is open for business now and offers a range of standard features including replies tab, direct messaging, and friend lists. Bonus features include built in support for Jabber, a mobile client, and for current Twitter users, Jisko supports importing Tweets and posting back to Twitter, so you can switch while still continuing to use Twitter. An Adobe AIR desktop application is on its way.
For those who like their platforms open source pure, the entire code base is available on Launchpad here. There appears to be an API as well, but it's not clear whether Jisko supports the OpenMicroBlogging, the standard supported by Identi.ca that allows cross install posting and reading.
My first impressions of Jisko are not great. The look of the service doesn't excite me, and there's really no defining features that set it apart from the growing army of Twitter clones. The site comes from Spain from what I can gather (the IP address points there, even if the domain itself is protected by Dreamhost) and the support wiki and documentation are all in Spanish, and the English parts of the site are only just in English, which isn't going to help with global uptake.
However, the integration of the Twitter API does make for an interesting twist as it lowers the barrier to entry, allowing people to switch without having to give up Twitter.
There are now dozens of these sorts of sites in Europe catering to local audiences and I have no reason to believe that Jisko will break through globally, but stranger things have happened.
(via Killer Startups)