Since Glass was announced, it has been rumored that it was running a skinned version of Android. It was then confirmed several days ago that it was for sure running Android 4.0, Ice Cream Sandwich. Now that some developers have received their Explorer Edition of Glass, they have hacked the software enabling them to view the native Android operating system. In addition to this, they have also been able to side-load Android applications.
While it is great that the device is hackable to the point that vanilla Android can be used on the device but this may cause issues with the battery life and the speed of the device. This could be an issue because the specially made timeline and cards that originally run on the device are made to save battery life.
Only time will tell to see what will come out of everything the developers will be able to do with their devices.
Source | SlashGear