Mike release Operator 0.8, which picks up RDF (RDFa en eRDF) from HTML pages, and adds actions to it. I blogged earlier about the beta and wrote a script for it for chemical RDFa. At this moment, Chemical blogspace and RDF for Molecular Space (see this blog) are using chemical RDFa to semantically markup molecular information.
The new Operator release (download) has one notable API change: it now uses "RDF" as key for semantic information; the add-on now supports eRDF too. So, when installing or updating to version 0.8, you also need to update the Sechemtic user script to version 1.1 or better.
Installing Operator scripts is a bit more work than Greasemonkey userscripts. Save the script to your home directory, or any other place you can easily find on the hard disk. After installing the Operator add-on, click the Options button:
For the RDFa script to work, you need to make sure that the Display style is set to Data formats:
Then you can go to the User Scripts tab, and use the New button to add the script you downloaded and saved to your hard disk earlier:
Then, after rebooting Firefox, looks like MS-Windows :(, you can go to Chemical blogspace and look up molecules, and see output like that described in RDFa Operator in action on Cb.