Having said that, there are a number of differences despite the similarities on the surface. Jaiku comes from a “presence” background allowing bluetooth proximity, phone idle time, ringer mode and other things to trigger state changes – the messaging came later. Twitter, on the other hand, is primarily messaging, which as we all know, is just a flexible and manual vector for presence information.
There is definitely a case of Twitter and Jaiku influencing each other. Just take a look at the pages on their respective sites. The presence aspect on Jaiku is a pretty interesting one, especially with the GPS aspect I saw in the Mobile Edition’s menu options.
(Source: Jyri Engeström)