In short, it's not a product announcement. When Abrash was hired at Valve, he was encouraged to find his own interesting project to work on. Seeing the rise of wearable computing as an "inflection point" similar to Quake (which pushed things like networking and 3D graphics into ubiquity), he decided that was something he, and Valve, should be ahead on.
"By 'wearable computing,'" Abrash explains, "I mean mobile computing where both computer-generated graphics and the real world are seamlessly overlaid in your view; there is no separate display that you hold in your hands (think Terminator vision)." Google is working on something similar, of course.
In other words, Valve hired a guy to do whatever at its game development company, and he decided to research a type of computing that doesn't exist yet. If nothing else, this is an indication of just how much money Valve has.