Minecraft wiki entry for Development_versions, associated text: New statistics: Distance by Horse, Animals Bred, Junk Fished, and Treasure Fished.
Rewrite of the system.
Now ties in with the scoreboard system.
Added 744 new objective criteria that were previously tracked with statistics and achievements.
Are now per world/server
Data for a block, item, or mob doesn't appear in their respective tab in the Statistics screen unless the player has crafted/placed/mined that block, crafted/used/depleted that item, or killed/was killed by that mob.