I've gotta say I'm more looking forward to the updated Qt-webkit in Qt 4.8 than I am to the v8 engine. The current Qt-webkit is really showing it's age. (It was forked from mainline Webkit years ago and never updated.)
You finally mentioned me after all the news submits I did :-) thank you!
Qt 5 is not likely to use V8, Qt 5 is already using V8 :)
While V8 is fast, Chromium crashes with wild abandon on my 32-bit installations of Kubuntu and with annoying frequency on the 64's. Rekonq, which uses WebKit, but a different JS engine I believe, is a rock. Throw multiple windows with multiple tabs all loading at once its way and it just purrs along.
Of course, making it all better on Chromium is a cutesy, Star Trek-inspired, "He's dead, Jim" failure alert. I wonder if that will become par for the course for KDE users?