This is what they were working up to.
Remember back in the old Everquest days when they implimented Alternate Advancements? This feels like a natural progression of that - Diablo III will be adding Paragon levels to the game with the 1.0.4 patch.
How Paragon works is, once any character reaches level 60, all experience gained after that point from monsters will add to Paragon levels, with a cap of 100. Every Paragon level rewards with core stats (Str, Dex, Int, Vit) and 3% Magic and Gold Find. The portrait will also reflect the Paragon levels earned with a new, stacking border. Though it's not level 61, getting a first Paragon level will require about as much work as 59-60, and will get harder from there. You are going to be in it for the long haul if you want to get maximum Paragon. To compensate, Gold/Magic Find are being capped at 300% by level 100, meaning you can drop the Find items by the time you don't need it anymore.
Further questions are answered at the Diablo III blog, including a diagram of what Paragon levels will look like to players.
Julian "Mirai" Williams