Blizzard has noticed a lot of players losing interest in Diablo 3 once they hit the level cap of 60. They're going to introduce a Paragon system in patch 1.0.4 that will hopefully reignite players' interest in end-game content.
After the patch goes live, level 60 characters will continue to earn experience from killing monsters. This experience will earn them Paragon levels. Each Paragon level will boost the character's core stats by the same amount as normal leveling. It will also bump up Magic Find and Gold Find by 3%. The end result is that players won't have to keep gimping themselves with Magic Find gear to get good drops, and they'll get a sense of progression even after level 60.
"The first Paragon level should take about as long as it took most players to get from level 59 to 60, and the experience requirement will rise from there," said director Jay Wilson on Battle.net. "The time to reach the upper Paragon levels approximates the long-term time investment required to get a level 99 character in Diablo II."
I suppose this new system might hold players' attention. It feels like a system that, sadly, would've been more effective if it was introduced three months ago when everyone was still playing. It seems unlikely that someone would return to the game just for this feature.
Blizzard previously admitted that farming the game over and over for better loot is "not enough for a long-term sustainable end-game." This Paragon system isn't really changing that. It makes the item hunt a bit easier and gratifying but the item hunt remains the sole reason to keep playing. That probably won't change until Patch 1.1, which will introduce player-versus-player combat.
Patch 1.0.4 will also adjust the difficulty level of the game, improve Legendary items and tweak all of the classes. The patch is expected to arrive by the end of the month.