I've been pretty pessimistic about Glass's chances for success as a consumer product for any number of reasons. The greatest challenge Glass has to overcome is the existential question: why should people wear it on a daily basis?
Adoption of new technology form factors are driven by a narrow set of killer apps. I don't see a mass market killer app for Glass.
Context is profound. And using context as a trigger is an intriguing concept. Google bet the farm on serendipitous, contextually driven search long ago when they began development of Google Now.
However, I think Phil and I are looking at the notion of context from different sides of the glass. My suggestion that context is king in eyeware computing is more of a developer guideline - that apps that developers build need to be contextual - as opposed to Phil's suggestion - that Glass is an inherently hyperaware, contextual device. At this stage, I don't find Glass to be any more hyperaware than one's smartphone, and in fact, in many ways less aware because of Glass's limited battery life.
Glass is a computer, just like a smartphone. It has certain unique traits and marginal value. It has the potential to be hyper-contextual because
1) it's hands free, and thus nonintrusive
2) there's a heads up display that can provide contextual data cues
3) it's is always there
4) the first person camera could enable fine grained contextual computing. These aspects of the device lend themselves to contextual computing if Glass knows what one is doing within a given 5 second window of time. Unfortunately, without running the camera 24/7 (which will kill the battery very quickly), Glass really has no clue what one is doing within a given 5 second window of time.
Of course, Phil described a few apps that don't require quite the level of contextual awareness I described, such as the need to purchase vegetables when one walks into the grocery store. Location is a powerful contextual trigger. However, location doesn't fundamentally make use of Glass's unique characteristics. Sure, Glass can present location-contextual data in a friction-free manner, but it doesn't justify the cost of wearing Glass.
However, if we ignore battery limitations, Glass will be the ultimate hyperaware computing device. Once Glass knows what one is doing, it can really start to provide useful information.