The open semantic framework (OSF) uses the Drupal CMS via the conStruct plug-in modules. conStruct is a distro of the Drupal framework specifically developed to provide management, access and visualization of structured content. conStruct is built on the structWSF platform. Here are more links about conStruct:

• Demo
• Design Overview - the best starting place to get oriented to conStruct
• Installation Guide
• Features
  • Datasets -- the basic construct within conStruct
  • structWSF -- the platform-independent Web services framework that underpins conStruct and provides the basis for a Web-oriented architecture (WOA) for application-independence and interoperation at Web scales
  • Tools -- a growing set of tools geared to using and managing structured data
  • structDisplay -- the complementary module for designing the templated data displays that keeps the presentation layer generic, driven by the data at hand
  • structOntology -- another complementary module that helps manage how all of this structure relates to each other
  • Full-text, Faceted Search -- via Solr, because we want to find stuff in a structured way
  • Structured (RDF) Data -- via Virtuoso, because, after all, there needs to be a great-performing RDF foundation
  • Import/Export -- well, let's talk to outside world, and
  • Packaging Options.
• Individual Tools

Like Drupal and structWSF, conStruct is of course free and open source.