Its from a team of Painters, called Massive Voodoo. I used this tutorial: http://www.youtube.com/watch?v=LRt_Pp_n_II
They go some steps further, but i use them only for gaming purposes, and I finished after painting highlights.
You got any link(s) to the techniques you used?The weathering looks close to perfect and it's the most life-like effect I've seen in all my years painting and modelling! O.o