Snapshot 13w10b, Minecraft 1.5, Minecraft 1.5.1, Minecraft 1.5.2, Snapshot 13w23b, Snapshot 13w24a, Snapshot 13w24b, Minecraft 1.6.1, Minecraft 1.6.2
I created a superflat world with and end style and after a long time flying around I found this wrongly generated ender crystal (screenshot-1.jpg, foreground).
The wide part of the bedrock block (belongs to the crystal) should be at the bottom (like at the crystal at the back, same image)
Technically the crystals are only 1 block higher than they should be.
creation template for that superflat world:
EDIT: After reloading the world (to check the creation template) the crystal corrected it's position tho someone should look after that.