All of then I have seen are 1.6-1.7 updates. I haven't seen anything like this with the 1.8 biomes. Unless you go out REALLY far from spawn you aren't likely to... unless you are talking about the ocean monuments... they caused some problems lol. Smp7 has one in the middle of a desert
This phenomenon is due to technical reasons. Check the explanation below if you're willing to read my tech-writing. The terrain generator as of Minecraft Version 1.7 and the generator prior to 1.7 are completely separate and unique. Because of their diversities, newly generated chunks next to pre-1.7 chunks will not respond to those older chunks, thus creating an unsteady boarder between them. This is may also be why the nether has never taken advantage of the bigger build limit. If it was attempted, there would be massive gaps between old and new terrain without bedrock, thus allowing survival players to get on top of the nether in a legit manner. Mojang doesn't like us to have access to empty space (I can understand this because of also the Amplified world type, and the upcoming "New" End). The 1.7+ generator generates the biomes in a realistic manner by following a temperature system. Each biome is assigned a temperature value to indicate its type of climate. The generator will try to generate biomes with similar temperatures by each other. Therefore, dry biomes like deserts, mesas, and savannas will almost never generate next to cold biomes, such as ice plains and cold taigas. Nothing I've stated about the current world generator doesn't apply to terrain generation before 1.7. Biomes had almost no restrictions to generate back then. The mushroom islands were one of the few biomes that had such restrictions with other biomes: they must be touching an ocean.