We're actively researching Google's V8 JavaScript engine for use in Qt. For legal reasons, we had to take our work underground where it doesn't belong. But now we're back:
http://qt.gitorious.org/qt/qt-script-ng
For the moment, this is a full Qt clone. You can find more information about this project in the QtScript wiki. We've also created a mailing list for JavaScript/Qt development, and an IRC channel on FreeNode, #qt-script. If you have an interest in (the future of) Qt's JavaScript integration (in QML, QtWebKit, or custom application embedding), you're welcome to join.
The status of the V8-based back-end is that we still have some QtScript API that's not implemented, and there are autotests failing (QTBUG-17640), but several of the QtScript and QML examples and demos run. Aside from behavorial compatibility with current Qt, we also need to ensure that there aren't any performance gaps in the C++/JS layer before a V8-powered Qt can become a viable solution. As I mentioned in a previous post, we're simultaneously looking to trim the fat of our current APIs to make a switch feasible.
