StatusNet

StatusNet (formerly Laconica) is a FOSS microblogging server written in PHP that implements the OStatus standard for interoperation between installations. While offering functionality similar to Twitter, StatusNet seeks to provide the potential for open, inter-service and distributed communications between microblogging communities. Enterprises and individuals can install and control their own services and data

Programming Language
PHP
License
Open Source
Developer Name
http://identi.ca/