More New Details on v1.0.5
The Players X type system is translated as “Monster Power” and players  creating games with level 60 characters can set it from 0-10 at game  creation. You can not tweak it during a game, such as by turning it up  before a boss fight.
At higher levels the game difficulty is increased, with correspondingly  better experience gain and item rewards. Details are still unspecified  on just how they’ll be increasing the difficulty, and on what “better”  items means. More, higher quality (Sets/Legendaries) items, higher level  items, or all of the above.
To unlock the Infernal Machine players will have to gather ingredients  from all four acts, so it will presumably not be a short and easy  assembly process. (Apparently even longer and more involved than Diablo  2′s Pandemonium Event.)
The Infernal Machine level has “a completely new architecture”  (tileset?), but no new bosses or monsters. (Presumably the “uber” bosses  will be palette shifted and have some new abilities, but we’ll wait for  D3X for entirely new monsters.)
The Infernal Machine reward is a new Legendary ring only available from  this quest. The biggest news is that it will DiabloWikiBind on Account.  So no trading or selling or gifting, but you can use it with other  characters on your account.
Other details remain vague, so it seems like we’ll have to wait for the  actual patch to find out every last detail and start hunting those new  uber rings. It seems pretty likely the ring will be something like the  Hellfire Torch, with guaranteed great stats, but enough variability that  you’ll probably want to find several of them while trying to get a  better roll, and perhaps a roll better suited for each character class.
Source: 
http://diablo.incgamers.com/