The "fat jet approach" was initiated first by Jon Butterworth in: J.M.Butterworth et al, Phys.Rev.Lett. 100,242001(2008),[0802,2470]. It has been used in ATLAS recently for WH(bb)&ZH and published in ATL-PHYS-PUB-2009-088 and ATL-COM-PHYS-2009-345.
There were several Notes published at the time of Physics TDR or soon after.