Blurring different layers of vision?

How would I use a camera to make everything past a certain distance appear to be blurry whilst everything with a certain distance remain clear?

I want to do this in a 2D environment just to give my game world a feeling of expansiveness. I want to do this much like Little big planet does.

Please Help :)

You could use two cameras, adjust the near and far clipping planes, adjust the depth (the camera rendering order), set the Clear Flags for the first one to Depth Only and attach the Blur image effect to the second one.

You could also make use of layers to get more control of which part of the scene is rendered by which camera.