Minecraft 1.5 will be a huge update, and today we receive an early present from the team at Mojang. Today the Minecraft 1.5 Prerelease is available for download, which will be 99.9% like Minecraft 1.5 (the only difference is fixes for bugs). The full changelog between 1.4.7 and 1.5 is adding Redstone Comparators, Hopper blocks, Droppers, Activator Rails, Daylight Sensor, Trapped Chests, Weighted Pressure Plates, Blocks of Redstone, Nether Quartz, Block of Quartz, more detailed death messages, and mobs are harder on higher difficulties. Finally Mojang adds "Removed Herobrine" at the end, and it's up to your imagination what that means. You can get the jar at the source link.Source: Mojang