1) The document discusses a system to enable semantic search across heterogeneous wiki systems using Semantic Web technologies.
2) Key aspects of the system include a common semantic model based on the SIOC ontology to represent wiki structure and contributions, data extractors to translate wiki data to RDF, and an application with a user interface to enable semantic search and browsing across different interlinked wikis.
3) The system was able to semantically search and link information across 5 different wiki sites containing over 3000 articles and 700 users.