The bulkiest parts are the battery riding on the right ear and the projector, though these things will presumably shrink over time. (On the battery front, have a look at LG Chem's wire-like battery tech and UCLA's developments in supercapacitors.) The image is bounced off of a prism and focused directly onto the wearer's retina. Interestingly, the fine-tuning of the focus is apparently achieved in a primitive way: By physically adjusting the distance of the prism from the eye.
"The biggest challenge for Google will now be to make the Google Glass also usable for people with normal glasses," writes Missfeldt. That's no trivial matter, as by his reckoning that's more than 50% of the population in some countries; by your correspondent's observation, countries like South Korea and cities like Hong Kong have an insanely high percentage of children wearing eyeglasses.
"In this case the Google Glass has to be placed ahead of normal glasses—which doesn't [work well]. Or Google has to manufactor [sic] individual customized prisms, but this would be considerably more expensive than the standard production."