The Ubiquity RDFa parser can be used to check a document in the browser, using this bookmarklet:
The RDFa parser itself has been tested in FF, IE, Safari and Chrome, and works fine. However, there are issues with loading the validator in Safari and Chrome, making it currently unusable in those browsers. Also, since versions of IE prior to IE8 don't support fixed positioning, the checker's layout is useless in those browsers. And finally, since IE8 has unpredictable formatting, it really depends on the source document as to whether the checker's layout is legible.
In short, for the time being, the recommended way to check your RDFa with this bookmarklet, is with FF.
Drag-and-drop the link above to the bookmarks area.
Drag-and-drop the link above to the bookmarks area, and then click 'OK' to accept the name for the bookmarklet.
Ensure that the bookmarks bar is showing, and then drag-and-drop the link above onto it.
Click on the right-hand mouse on the link above, and choose 'Add to Favourites...'. A dialog-box will follow, in which you will need to set the field 'Create in:' to 'Links'.
To test the checker, load the simple Twitter sample, and click on the 'Ubiquity RDFa' bookmarklet. After a short pause, you should see a message in the bottom right, informing you that the library has loaded, and then a large gray area will appear, showing all of the triples that are available in the document.