I think on the whole you'd obviously rather have this capability than not, and in the hands of developers interesting stuff will happen.
But I chuckled a little thinking back to all the Fitts's Law discussions that used to go on about the Mac versus Windows menus - on the Mac, the hit area is higher because you can just hit the top of the screen with your mouse. On Windows, it was always lower, because you had to aim below the title bar. This reminded me a bit of that - full fledged touches are dead easy to get right, hovering slightly less so. So I'd hope if this makes it into the final platform (or inevitably gets copied) that there's a lot of guidance to developers to use it only for enhancing existing gestures, instead of making it a primary mode of interaction.
But I chuckled a little thinking back to all the Fitts's Law discussions that used to go on about the Mac versus Windows menus - on the Mac, the hit area is higher because you can just hit the top of the screen with your mouse. On Windows, it was always lower, because you had to aim below the title bar. This reminded me a bit of that - full fledged touches are dead easy to get right, hovering slightly less so. So I'd hope if this makes it into the final platform (or inevitably gets copied) that there's a lot of guidance to developers to use it only for enhancing existing gestures, instead of making it a primary mode of interaction.