For those interested in the Semantic Web as much as we are at Logilab, the announce of the new DBpedia release is very good news. Version 3.2 is extracted from the October 2008 Wikipedia dumps and provides three mayor improvements: the DBpedia Schema which is a restricted vocabulary extracted from the Wikipedia infoboxes ; RDF links from DBpedia to Freebase, the open-license database providing about a million of things from various domains ; cleaner abstracts without the traces of Wikipedia markup that made them difficult to reuse.
DBpedia can be downloaded, queried with SPARQL or linked to via the Linked Data interface. See the about page for details.
It is important to note that ontologies are usually more of a common language for data exchange, meant for broad re-use, which means that they can not enforce too many restrictions. On the opposite, database schemas are more restrictive and allow for more interesting inferences. For example, a database schema may enforce that the Publisher of a Document is a Person, whereas a more general ontology will have to allow for Publisher to be a Person or a Company.
DBpedia provides its schema and moves forward by adding a mapping from that schema to actual ontologies like UMBEL, OpenCyc and Yago. This enables DBpedia users to infer from facts fetched from different databases, like DBpedia + Freebase + OpenCyc. Moreover 'checking' DBpedia's data against ontologies will help detect mistakes or weirdnesses in Wikipedia's pages. For example, if data extracted from Wikipedia's infoboxes states that "Paris was_born_in New_York", reasoning and consistency checking tools will be able to point out that a person may be born in a city, but not a city, hence the above fact is probably an error and should be reviewed.
With CubicWeb, one can easily define a schema specific to his domain, then quickly set up a web application and easily publish the content of its database as RDF for a known ontology. In other words, CubicWeb makes almost no difference between a web application and a database accessible thru the web.