Or... just add a privacy filter to the display. http://www.google.com/search?q=privacy+filter+display No need for webcams, special software that needs to run on all possible OS'es etc.

Sounds like really "fun" technology, but I wonder: is peeking-over-the-shoulder really enough of a pain point to justify the cost of this software? I suppose it would be ideal for surfing porn at work, provided that it blurs effectively enough.

Probably not for most people. Might be useful for receptionists in a public area. Useful if you can make it a requirement for eg. nurses stations in a hospital.

A version built in to ATMs would be good.