The ceiling limit wasn't raised, but Notch changed something in the code so that it will be easier for modders to raise the height limit in the future.
Some guy on reddit posted a 20kmX20km map to show off the new terrain generator in comparison to the old one.
The old generator
The new generator
As you can see, snow and ice aren't implemented yet, but look at the size of those oceans. That one on the bottom left must be at least 75kmē!
Speaking of which, I generated a new world earlier and found myself on a small island with a single tree and all I could see around me were two other treeless islands. This should provide me with an interesting challenge until 1.8 is released proper.