Yep. There has been some talk about this before.
There’s a longer article that also just came out on this story, here:
http://silverdoctors.blogspot.ca/2012/03/tungsten-filled-1-kilo-gold-bar.html
The article claims that ClintBilly and his money guys ordered a bunch of these bars to pay off China and to stick in Fort Knox. Who knows? It’s the kind of thing that he might very well have done.
I recall speculation that security at Fort Knox tripled not to protect the gold but to protect discovery of what was there.