xDof is an amazing plugin to have a depth of field in a pair of second, i realy like this plug, but it doesn’t work with Vray 
at this moment i havent’ purchase xDof just for that reason, but i realy realy wish to have it…
so i hope which the Chaos Ninja Developer think about it 
xdof does work with vray read here http://vray.info/topics/t0050.asp
you need to enable gbuffer z depth i believe