Sightsync will eventually get to image recognition, so I paid some attention to those applications at ARcade and VRLA. This post sorts out a couple of them and give personal views.
Because image recognition is still energy-intensive on mobile platforms, its current usage is so limited that some projects are duplicating. Also, I personally sense that those projects are still competing and focusing on technology: the accuracy of recognition, lacking an UX or "practical" perspective. With that going, technology is evolving: space recognition will be available soon.
uSens Demo and Space Recognition