The Google Glasses project is the second big step towards a more cybrid experience that we see in a very short period of time, the first one being Apple´s SIRI.
Although the first prototype looks pretty fine, I really missed something that could definitely be embedded in those glasses: eye cameras.
Using eye tracking technology applied to 2 cameras facing inwards to the eyes, Google could help the users track some indicators like the attention level, the emotional state, the fatigue level etc. Apart from that, tracking all those biological parameters would definitely help Google serving better ads.
The picture below shows a simple draft of how I think Google Glasses 2.0 could look like: