I am trying to make soft shadows so that they will cast on every object in the scene. As you know, shadow volumes are good, because shadow caster receives shadow by itself. However, the main disadvantage of shadow volume is that they are hard-edged (non-soft). So I asked myself – how can I make shadow volumes that become soft edged? I found some algorithms and solutions on the net, like to do several shadow volumes in different alpha values… Oh yes, they are too slow in real-time graphics (imagine few objects that cast shadows and all this runs at 14fps on my gf6200). But the real idea of soft and fast shadow volumes came to me when I made post-process effect called bloom (aka fake HDR). One of the bloom elements is a screen space blur…Therefore, I thought why we couldn’t use this blur element (separable convolution) to blur our shadow volumes? 
Here you can see results of my expermentations:
