It hadn't even crossed our minds to question what the operating system was that ran on Google Glass, but looking back, it turns out that Google never specifically said that it was Android, we just all assumed it was. Of course, that assumption was completely right, and Google's CEO Larry Page confirmed that Google Glass runs Android during the Q1 earnings call
The comment came in response to a question about what kind of engagement increase companies should expect with new products like Glass. Page responded, “Obviously, Glass runs on Android, so [Android] has been pretty transportable across devices, and I think that will continue.”
So, that answers that. It had been assumed that Glass ran Android, but there had also been some speculation that Glass was running a custom OS that was separate from Android. Maybe it didn't really need confirmation, but we're glad that's been laid to rest anyway.