A noted rival to the Google Glass is the Star 1200 XL it is a VR/AR system from Vuzix. Although it being considered a rival they both do very different things, the Glass is for constant use and small screen offers updates rather than viewing content. The Star is currently more for short usage with its slightly bulky design but it contains a lot more, it offers 1080 camera and two wide screen displays at 852×480 which is equivalent to a 75″ display viewed from 10 feet. Here is a really good review i found on youtube.
Noted Rival – Star 1200 XL