Some of it is still going on, right now I'm specifically thinking of when the death camps were liberated. In the comments to the previous post BobG said
I had an uncle who was in the army at the liberation of Buchenwald; he had difficulty keeping his men (he was a master sergeant) from shooting the guards out of hand when they saw what was going on. Most people that yammer about the holocaust have no idea what they are talking about.
If you haven't seen it, borrow/buy/rent the 'Band of Brothers' disc* with the episode 'Why We Fight' and watch it. It gives a pretty good idea what the troops found when they discovered some of these places.
*If you haven't, get and watch the whole series, an excellent piece of work.