In a recent article on PC Gamer, Minecraft creator Markus "Notch" Persson explained a new leveling system for Minecraft versions to come.
“I’m a big roguelike fan,” explains Notch. “It’s really fun. The idea is that you level up really, really fast. You can grind away and level up fast if you want to, or you can just play as normal and level up that way. The longer you play, the bigger the risk of dying becomes. It’s the part that really works. If it feels like it’s too harsh, we might make it half or something like that. But the fact that you lose everything – you lose all your inventory anyways.”
This is looking like it's more and more to do with the much anticipated "Adventure Update" moniker that Patch 1.8 has been dubbed with.