I'm sure Google realizes the strategic and technical value of a second open-source browser implementation. Just because they're using WebKit today doesn't mean

I'm sure Google realizes the strategic and technical value of a second open-source browser implementation. Just because they're using WebKit today doesn't mean they will forever (or for everything). Gecko is valuable as an alternative and as a way to "keep web standards honest". A WebKit monoculture would eventually bake in too many hidden assumptions.