Having gotten all worked up over the new Paragon System for Diablo III yesterday, I'm pleasantly surprised to see that patch 1.0.4, which includes the new late-game leveling system, is going to roll out today.
Currently, the game is down; Blizzard estimates that scheduled maintenance will be completed by 1:00pm Pacific in the Americas and 6:00am Pacific on August 22 in Europe. For the time being, I suggest taking a look at the full patch notes.
Although the Paragon levels are probably the most noteworthy addition from a blogger's perspective, there is quite a bit going on here, particularly when it comes to Legendary items and enemy difficulty. You'll also want to scroll all the way down to the class-specific changes, of course.