I do not use Photoshop, but you should be able to emulate the effect of a short focal depth, given a suitable photo, i.e. one with a simple distinction between foreground and background. In principle you mark out the foreground and split it into a separate layer, then apply a diffuse mask to the background layer. There is probably a tool to automate this, but failing that you can simply:
- Duplicate the photo into a second layer.
- Manually erase the background from the foreground layer.
- Apply a diffuse mask to the background layer.
Voila! Well something like that.
Incidentally the effect is not exclusive to dslr's. Any camera with a manual aperture setting can achieve this effect by opening the aperture, thus shortening the focal depth. My Fuji compact has a manual mode allowing the aperture to be set.