There's a Charles Stross novel from a few years ago, called "Halting State", which pretty solidly covers virtual worlds, and has this sort of augmented reality tech as a natural part of the world.
And this is a link to a vid of him talking at Google back in 2007.
http://www.videosurf.com/video/authors-google-charles-stross-57245801
If you have missed "Halting State", you might have missed a few obvious complications.
