Minecraft update 1.7 to completely rework terrain generation

it’s that time again! “That time” being the fateful occasion of a Minecraft update that completely shakes up how its procedural world maps are generated. In addition to introducing new biomes, the upcoming 1.7 patch will include new code that should create more logical climate zones, while doing away with vast, featureless oceans.  www.All909.blogspot.com
The Minecraft blog has given us a look at how terrain is generated now…

And how it will be generated post-1.7…

Unfortunately, it seems like we’re losing the realistic continent shapes and land-to-water ratio. But in return, we should have better biome placement and more logical transitions. No more deserts right next to a snowy forest. This has been accomplished by grouping all the biomes into four meta-biomes: snowy, cold, medium, and dry/warm. Among these groupings are three new biome types, including redwood forests, rocky cliffs, and canyons.