http://www.homebrewtalk.com/f73/pious-westvleteren-12-style-quad-multiple-147815/
Here are my two "house" recipes for cloning a Westvleteren 12. I brewed the New World (this recipe with specialty grains) once and the Traditional 3 times. I prefer the Traditional but as previously stated, in a blind tasting my New World scored 45 points avg and was unanimously chosen as being dead on for the real thing by the judges. I think with my most recent changes to my Traditional recipe (D2 syrup, decoctions) it will also be more or less dead on, and true to style as well.

If you didn't read all the way through the admittedly long Westvleteren 12 clone group brew thread, we discussed the aspects we did know about the authentic beer, and the many things we didn't. Suffice it to say, they are both REALLY close and make REALLY good beers.