Looking to blur out a background to reduce distractions? In Lightroom 3, use the adjustment brush with Sharpness at -100. If this is not enough blur, do it again: click on New to start a new adjustment, and paint a second time.
Also consider using the graduated filter with -100 Sharpness to simulate a shallower depth of field where the sharpness drops off gradually. UPDATE: If you blur out an object that you want to keep sharp, use the adjustment brush and paint back over the object with +100 Sharpness to restore its sharpness!
Is this cool, or what?