Has Mozilla considered enabling this by default for certain sites on white-list (Flickr, PicasaWeb, etc.)? This way this kick-ass feature could be enabled by sites/users that really benefit from it without breaking the rest of the web.
Thanks for posting this Tom. I've been playing around with WebRunner 0.7 as I really like the idea of making Web Applications first class citizens on the desktop.
I've noticed some performance issues compared to Firefox though. Namely, WebRunner takes a lot longer to start-up compared to Firefox and the page rendering seems a bit off too.