OpenCalais.com - Semantic Web and Metadata

OpenCalais is new web service which aims to construct a more semantic web by offering metadata enrichment to web apps and services. Calais attaches semantic metadata to content you submit—associating it with relevant people, places, facts and events. From there, users can build graphs, networks, trees, whatever to display links—improving site navigation, adding contextual information, creating folksonomies, etc. Essentially, bloggers, publishers, and all sorts of web sites can use the service to automate metatagging increasing search relevance and accessibility on the internet. Content is returned in a portable and interoperable format so it can be integrated into social networks, widget, etc. Calais is available for free to both commercial and non-commercial parties. To get started, you’ll need to download the instructions from the site and get the API key. Afterwards, you can submit your content and Calais will identify semantic parts therein. The results are stored centrally.

“We want to make all the world's content more accessible, interoperable and valuable. Some call it Web 2.0, Web 3.0, the semantic web or the Giant Global Graph - we call our piece of it Calais.
The core of Calais is our web service. We're working to make this service more accessible by developing sample applications, supporting developers and offering bounties for specific capabilities.”

Calais automates the generation of semantic metadata providing advanced sorting and filtering of content. It does this in a matter of seconds, which is something you couldn’t do simply by hand tagging information. The content is then more accessible to everyone.

Will this remain free? How easy is it for users to implement? How well does this actually work? Will it be adopted by more mainstream users?