EVGA Geforce 660
Stained Glass, Ice, and any block that has a changed opacity other than 255 has a rendering error. The clouds are implemented so that it appears to be above any of these blocks. This is the only version that has had this, I went back to my 1.6.4 jar to check and it's rendering fine.
Steps to Reproduce:
1. Build near cloud level with any block that has a changed alpha/not solid
(EDIT: Might need to be on Amplified world type)