Last summer, while Twitter was struggling to keep its servers running consistently, a number of rivaling microblogging services like Plurk and Rejaw arrived on the scene, ready to capitalize on the imminent exodus of Twitter's disgruntled users. Twitter, however, was able to turn its fortunes around and is now just about as stable as any other online service. It is also growing at an impressive rate and has become the de facto standard for microblogging in most users' minds. For Twitter's competitors, however, this has meant that there are fewer users to go around, and today, Rejaw announced that it will shut down its servers on May 31st.

Rejaw has stopped accepting new sign-ups and will allow its users to export their data as an XML file.

In the absence of real interoperability between the different microblogging and messaging services, Twitter, which already has the most users, will only gain momentum. With and, we do have real, open-source, standard-based alternatives to Twitter, but the sheer momentum behind Twitter will make it increasingly hard for newcomers to break through to a large enough audience.

In many ways, this is quite a shame, as most of the innovation around Twitter has come from third-party developers, while services like Rejaw, for example, tried out a lot of interesting features and user interfaces. Rejaw, for example, made 'real' real-time messaging a core feature of its platform.