Blizzard has launched the 1.0.4 patch for Diablo III, which, among other things, adds the Paragon system. This endgame content kicks in after players hit level 60, with 100 Paragon levels that increase core stats and improved magic/gold finding. Progress through these is indicated publicly with distinctive portraits every ten levels.
The patch also addresses several bugs and UI issues. A full list of patch notes is available here.