re: Google Glasses: Does This Make Sense?
Craig, the problem with this kind of technology is that while covered (fleetingly) by mainstream press it will be a long time, if ever, before it goes mainstream. Case in point - the Segway. It was too expensive and a product before it's time. Do you recall how other electric drive devices were perceived in 2001? Right, as expensive, and often flakey novelties or toys. However there are a few exceptions...like electric forklifts and other heavy-duty industrial tools. That is the niche where these products work - special applications. I have seen Segways used by law enforcement in crowd patrol in place of horses and in other types of extended patrol situations with good results, especially if fitted with GPS.
With respect to the Google Glass project, they will not even be available until late 2013 or 2014. It is likely that they too will not really be consumer devices, but rather industrial and institutional. Their most effective role will probably be as augmented reality overlay devices. The input controls are likely to be lightweight VR gauntlet type, but more like driving gloves, with sensors that allow interaction with objects in the overlay. Think: Fire Fighters able to overlay building elevations onto their view as they search for survivors; Tactical overlays for LEOs and military Spec-OPs; and replacements for HUDs in aircraft to name a few.
Commercial applications could easily be seen as a dashboard overlay for performance motocyclists where you'd look 'through' the instruments and gauges(safer than looking down). Not to say that some won't be bought for ahem, other purposes...
Finally, by the time Glass becomes available to John Q. Public they will likely be much more subtle than the gear worn in the French McDonald's incident and may even go unnoticed.