That's very sad news, because a lot of people who are designing mobile websites are really waiting for a extension like that.
And it's a market 10 times bigger then the desktop market (and growing every day!).
It seems when looking around for mobile development tools, most extension makers are missing the train all ready. It looks like they can't keep up with the enormous speed things are pointing more and more in a mobile direction. (look at my suggestion for a "mobile website maker with device detection" on the Wish List Page of this forum) if you like.