By the end of 2012, Google is expected to start selling eyeglasses that will project information and entertainment. The glasses will be like a smartphone with the lenses serving as a kind of see-through computer monitor. They are not meant to be worn all the time – but as needed.

The glasses are being built in the secretive Google X laboratory near Google’s main Mountain View, CA.

The glasses will use the same Android software that powers Android smartphones and tablets. They will be equipped with GPS and motion sensors and contain a camera and audio inputs and outputs. They will be fed by a 3G or 4G connection. The navigation uses head tilting to scroll and click. The low-resolution built-in camera  will be able to monitor the world in real time and overlay information about locations, surrounding buildings and friends in the area. The latter opens up some privacy concerns, as people might object to being filmed by someone wearing the glasses.

Of course, the glasses will be able to serve up advertising (this is Google after all).

Cost on the new glasses hasn’t been set – and speculation is all over the place – anywhere from $250-600 have been quoted.