This appears to be a wrapper for PyQt4's QTWebKit.
http://www.riverbankcomputing.co.uk/static/Docs/PyQt4/html/q...
http://www.riverbankcomputing.co.uk/static/Docs/PyQt4/html/q...
E.g. I use Qt 4.8 (via PyQt 4.9) and thus I have WebKit trunk from 2011-05-05 (r85855).
There is also PyQt4.QtWebKit.qWebKitVersion().
If you have the Qt source at hand, check src/3rdparty/webkit/VERSION.