Since Joomla is written in PHP, this code can help you to get freebase
identifiers:
http://developer.zemanta.com/wiki/helloworld/php
(don't forget to set the parameter "return_rdf_links" to 1
The second step -- pulling data from freebase -- can be done either
through RDF, or through MQL queries. You should consult Freebase
documentation for that.
bye
andraz