Syndication/systems

sciencelive/opencontent/CamTV/http://podcast.steeple.org.uk = php (with some simplepie, and some Zend/lucene)
PCF Miro Community = py/django https://git.participatoryculture.org/localtv Mirocommunities is also available as a hosted version (hosted by Miro), i.e. you can just create your online sharing site without having to install anything. Later, when you want to run your own server, you can then just install the software, and run it locally. That's a very good thing!
Oxford/openspires = Drupal / php / GPL
Steeple (Cambridge WP) = SOLR / JAVA, see Portal (Open source under ECL)
mediamosa (GPL?)
ARCA (php, GPL?)
xpert Nottingham: http://xpert.nottingham.ac.uk (php) source code available ? license?
http://galadriel.cetis.ac.uk/ensemble/ source code available? license?