I got this idea from hbo.com where the series page has a featured image that provides its own background.
My version allows you to set the height of the blurred background, the amount of blur, the position of the image in relation to the background, and the scale of the background image.
Conceived as installing into a full page width area, contained areas will give different results.
You can have the image centered vertically, or aligned to either the top of the blur or the bottom.
You'll have quite a bit of leeway in setting the blur and scale. Currently, Google Chrome (mac, at least) will display the blur differently than Safari, Opera, Firefox. This is not a flaw, as they say, it's a feature.