DiabloFans recently datamined a very interesting piece of information: torment difficulty! Nobody knows exactly what this new difficulty will be or how it will work, but chances are it's going to come after Inferno totaling at 5 difficulty levels. There have been many threads created on the official forums discussing this new difficulty, and recently Grimiku even posted a reply (although he didn't reveal anything). Here is what he said:
We'd like to give players more control over the difficulty settings, and we're looking at ways to accomplish that. It's a little early to share any details, but there was an interview prior to gamescom where Josh Mosqueira shares some of his thoughts about it. He mentions (at 7:30) that Diablo III has a great engine, but we constrain some of it's awesome potential by forcing players to replay the same Acts, quest, and levels over and over.